Metakaolin-based geopolymer cementing material and preparation method thereof

Abstract

The invention relates to the technical field of mineral processing, particularly discloses a metakaolin-based geopolymer cementing material and also discloses a preparation method of the metakaolin-based geopolymer cementing material. The metakaolin-based geopolymer cementing material provided by the invention is prepared from diatomite, metakaolin, sodium hydroxide and water. According to the metakaolin-based geopolymer cementing material provided by the invention, the diatomite is directly used for preparing the geopolymer cementing material, and the volcanic ash reaction activity of the diatomite is fully utilized. During preparation, the diatomite is firstly mixed with sodium hydroxide and water for pretreatment, so that the active silicon component in the diatomite is activated, and the molar ratio of SiO2 / Al2O3 in the raw materials is increased, thereby enhancing the compressive strength of the metakaolin-based geopolymer cementing material.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive utilization of minerals, in particular to a metakaolin-based oligomer gelling material and a preparation method thereof. Background Art

[0002] Geopolymer cementitious materials are environmentally friendly cementitious materials, and their production process has the characteristics of low energy demand and low carbon dioxide emissions. Metakaolin is the most commonly used natural raw material for synthesizing geopolymers. Geopolymer cementitious materials using metakaolin as raw material show physical and chemical properties superior to ordinary Portland cement, and have significant advantages in heat resistance and durability, so they are used in many fields such as infrastructure construction, heavy metal immobilization, and wastewater treatment.

[0003] Adjusting the SiO2 / Al2O3 molar ratio of the raw materials is an effective means to optimize the performance of kaolin-based polymers. By supplementing active silicon and increasing the SiO2 / Al2O3 molar ratio in the raw materials, the setting time of the geopolymer can be shortened and the mechanical properties of the geopolymer can be improved. Currently, water glass (sodium silicate solution) is the main active silicon supplement for the preparation of kaolin-based polymers. Although it performs well in improving mechanical properties, the temperature required in its production process is very high, generally up to 1300°C. The high energy consumption and significant carbon emissions restrict the low-carbon and environmentally friendly characteristics of geopolymer materials and increase production costs.

[0004] Diatomite is a sedimentary rock composed of diatom shell fossils rich in amorphous SiO2. It not only has good physical and chemical properties, but also is considered a potential auxiliary cementitious material because of its volcanic ash reaction activity. In particular, my country's diatomite resources are very rich and widely distributed. Using it for the preparation of geopolymer cementitious materials is conducive to its development as a bulk building material and the efficient utilization of diatomite mineral resources. However, there are still few studies on diatomite as an active silicon supplement to optimize the performance of metakaolin-based polymers. A Chinese invention patent (publication number CN102924035A) discloses a method for preparing diatomite polymer cementitious materials, which uses fly ash and diatomite as raw materials and uses water glass as an alkali activator to prepare geopolymer cementitious materials. This method not only requires calcination of diatomite, but also uses water glass as an activator, which increases the carbon footprint and cost of the geopolymer material preparation process, and fails to fully achieve low carbonization and cost control of the geopolymer preparation process.

[0005] Therefore, the present invention aims to seek a lower carbon method to apply diatomite to the preparation of metakaolin-based polymers, so as to promote the continuous progress and wide application of geopolymer material technology. Summary of the invention

[0006] The main technical problem solved by the present invention is to provide a metakaolin-based polymer gelling material. Meanwhile, the main technical problem solved by the present invention is also to provide a preparation method of the metakaolin-based polymer gelling material.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a metakaolin-based polymer gelling material, the raw materials for preparation are composed of the following raw materials in parts by weight:

[0008]

[0009] As an embodiment of the present invention, the raw materials for preparing the metakaolin-based polymer gelling material are composed of the following raw materials in parts by weight:

[0010]

[0011] As an embodiment of the present invention, the raw materials for preparing the metakaolin-based polymer gelling material are composed of the following raw materials in parts by weight:

[0012]

[0013] As an embodiment of the present invention, the metakaolin is prepared by calcining kaolin, and the mass percentage content of Al2O3 in the metakaolin is ≥35%.

[0014] As an embodiment of the present invention, the calcination temperature of the kaolin is 650-800° C., and the calcination holding time is 1-3 hours.

[0015] As an embodiment of the present invention, the mass percentage content of SiO2 in the diatomaceous earth is ≥60%.

[0016] The present invention also provides a method for preparing a metakaolin-based polymer gelling material, comprising the steps of:

[0017] S1: mixing diatomaceous earth, sodium hydroxide and water to perform pretreatment to obtain a pretreated material;

[0018] S2: adding metakaolin to the pretreated material, stirring and mixing, to obtain a mixed material;

[0019] S3: injecting the mixture into a mold and vibrating it, then performing steam curing, and then demolding and forming to obtain a metakaolin-based polymer gelling material.

[0020] As an embodiment of the present invention, the pretreatment time is ≥18 hours.

[0021] Preferably, the pretreatment time is 18-24 hours.

[0022] As an implementation scheme of the present invention, the steam curing time is 12-24 hours, and the curing temperature is 20-45°C.

[0023] The present invention also provides the use of the metakaolin-based polymer cementitious material of the present invention or the metakaolin-based polymer cementitious material obtained by the preparation method of the present invention as a building material.

[0024] The metakaolin-based polymer gelling material provided by the present invention uses diatomaceous earth directly for the preparation of the geopolymer gelling material, making full use of the volcanic ash reaction activity of the diatomaceous earth. During the preparation, the diatomaceous earth is pre-treated by mixing with sodium hydroxide and water, so that the active silicon component in the diatomaceous earth is activated, and the molar ratio of SiO2 / Al2O3 in the raw material is increased, thereby improving the compressive strength of the metakaolin-based polymer gelling material.

[0025] The metakaolin-based geopolymer cementitious material provided by the present invention does not need to add water glass additives with a high carbon footprint during preparation, thus achieving green and low-carbonization of the geopolymer raw material source. The present invention makes full use of my country's abundant and widely distributed diatomaceous earth resources, not only enriches the raw material system of geopolymer materials, but also further reduces the overall energy consumption, making the production of geopolymer materials more environmentally friendly and economical, and has far-reaching social significance and environmental protection value.

[0026] The raw material cost of the invention is low, the energy consumption of the preparation process is low, and it shows broad application prospects in the field of low-carbon building materials, and it has a driving effect on the green upgrade and sustainable development of the building materials industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a photograph of the metakaolin-based polymer gelling material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described in detail below through specific embodiments. The following embodiments are intended to further illustrate the content of the present invention in detail, but are not intended to limit the scope of protection of the claims of the present invention.

[0029] Example 1

[0030] This embodiment provides a metakaolin-based polymer gelling material, and the raw materials for preparation are composed of the following raw materials in parts by weight:

[0031]

[0032] The metakaolin is prepared by calcining kaolin produced in Maoming, Guangdong at 750° C. for 2 hours, and the mass percentage of Al2O3 in the metakaolin is 44%.

[0033] The mass percentage content of SiO2 in diatomaceous earth is 68%.

[0034] The preparation method of the metakaolin-based polymer gelling material comprises the following steps:

[0035] S1: diatomaceous earth, solid sodium hydroxide and water are mixed and mechanically stirred for pretreatment for 24 hours to obtain a pretreated material;

[0036] S2: adding metakaolin to the pretreated material, and mechanically stirring and mixing for 5 minutes to obtain a uniform mixed slurry;

[0037] S3: The mixed slurry is injected into a mold and vibrated, and then steam-cured at 40±2° C. for 24 hours, and demolded to obtain a kaolin-based polymer cementitious material.

[0038] The photo of the metakaolin-based polymer gelling material prepared in this example is shown in Figure 1 shown.

[0039] Example 2

[0040] This embodiment provides a metakaolin-based polymer gelling material, and the raw materials for preparation are composed of the following raw materials in parts by weight:

[0041]

[0042] The metakaolin is prepared by calcining coal-based kaolin produced in Shahe, Hebei Province at 800° C. for 1 hour, and the mass percentage of Al2O3 in the metakaolin is 39%.

[0043] The mass percentage content of SiO2 in diatomaceous earth is 81%.

[0044] The preparation method of the metakaolin-based polymer gelling material comprises the following steps:

[0045] S1: diatomaceous earth, solid sodium hydroxide and water are mixed and mechanically stirred for pretreatment for 18 hours to obtain a pretreated material;

[0046] S2: adding metakaolin to the pretreated material, and mechanically stirring and mixing for 5 minutes to obtain a uniform mixed slurry;

[0047] S3: The mixed slurry is injected into a mold and vibrated, and then steam cured at 25±2° C. for 24 hours, and demolded to obtain a kaolin-based polymer cementitious material.

[0048] Comparative Example 1

[0049] This comparative example provides a metakaolin-based polymer gelling material, and the raw materials for preparation are composed of the following raw materials in parts by weight:

[0050] 100 parts of metakaolin

[0051] 18 parts of solid sodium hydroxide

[0052] 42 parts of water.

[0053] The metakaolin is the same as the metakaolin in Example 1.

[0054] The preparation method of the metakaolin-based polymer gelling material comprises the following steps:

[0055] S1: Mixing metakaolin, solid sodium hydroxide and water, and mechanically stirring for 5 minutes to obtain a uniform mixed slurry;

[0056] S2: The mixed slurry is injected into a mold and vibrated, and then steam cured at 40±2°C for 24 hours, and demolded to obtain a kaolin-based polymer cementitious material.

[0057] Comparative Example 2

[0058] This comparative example provides a metakaolin-based polymer gelling material, and the raw materials for preparation are composed of the following raw materials in parts by weight:

[0059]

[0060] Wherein, metakaolin and diatomaceous earth are the same as those in Example 1.

[0061] The preparation method of the metakaolin-based polymer gelling material comprises the following steps:

[0062] S1: diatomaceous earth, metakaolin, solid sodium hydroxide and water are mixed and mechanically stirred for 5 minutes to obtain a uniform mixed slurry;

[0063] S2: The mixed slurry is injected into a mold and vibrated, and then steam cured at 40±2°C for 24 hours, and demolded to obtain a kaolin-based polymer cementitious material.

[0064] The performance of the metakaolin-based polymer cementitious materials prepared in the above embodiments and comparative examples was tested. The test method refers to the method for measuring the compressive strength of cement mortar in GB / T 17671-2021 "Test Method for Strength of Cement Mortar", and a universal press is used to uniformly load a solidified body with an area of ​​20 mm × 20 mm at a rate of 2400 N / s ± 200 N / s until it is destroyed.

[0065] The performance test results are shown in Table 1 below.

[0066] Table 1

[0067]

[0068] It can be seen from the data in Table 1 that the compressive properties of the metakaolin-based polymer gelling material prepared in the embodiment of the present invention are significantly improved unexpectedly compared with the comparative example.

[0069] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A metakaolin-based polymer gelling material, characterized in that: The preparation raw materials consist of the following raw materials in parts by weight: 10-60 parts of diatomaceous earth 40-90 parts of metakaolin 15-20 parts of sodium hydroxide 40-45 parts of water.

2. The metakaolin-based polymer gelling material according to claim 1, characterized in that: The preparation raw materials consist of the following raw materials in parts by weight: 30-50 parts of diatomaceous earth 50-70 parts of metakaolin 15-20 parts of sodium hydroxide 40-45 parts of water.

3. The metakaolin-based polymer gelling material according to claim 1, characterized in that: The preparation raw materials consist of the following raw materials in parts by weight: 30-50 parts of diatomaceous earth 50-70 parts of metakaolin 18-20 parts of sodium hydroxide 40-42 parts of water.

4. The metakaolin-based polymer gelling material according to any one of claims 1 to 3, characterized in that: The metakaolin is prepared by calcining kaolin, and the mass percentage content of Al2O3 in the metakaolin is ≥35%.

5. The metakaolin-based polymer gelling material according to claim 4, characterized in that: The calcination temperature of the kaolin is 650-800° C., and the calcination holding time is 1-3 hours.

6. The metakaolin-based polymer gelling material according to any one of claims 1 to 3, characterized in that: The mass percentage content of SiO2 in the diatomaceous earth is ≥60%.

7. A method for preparing the metakaolin-based polymer gelling material according to any one of claims 1 to 6, characterized in that: Includes steps: S1: mixing diatomaceous earth, sodium hydroxide and water to perform pretreatment to obtain a pretreated material; S2: adding metakaolin to the pretreated material, stirring and mixing, to obtain a mixed material; S3: injecting the mixture into a mold and vibrating it, then performing steam curing, and then demolding and forming to obtain a metakaolin-based polymer gelling material.

8. The preparation method according to claim 7, characterized in that: The pretreatment time is ≥18 hours, preferably 18-24 hours.

9. The preparation method according to claim 7, characterized in that: The steam curing time is 12-24 hours, and the curing temperature is 20-45°C.

10. Use of the metakaolin-based polymer cementitious material according to any one of claims 1 to 6 or the metakaolin-based polymer cementitious material obtained by the preparation method according to any one of claims 7 to 9 as a building material.

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