Preparation method of beta-c2s crystal structure

Abstract

The application relates to a preparation method of a beta-C2S crystal structure, and the specific steps are as follows: S1, calcium raw materials, silicon raw materials and a crystal structure regulator are mixed according to a calcium-silicon molar ratio of 2:1 to obtain sintered raw materials; S2, the sintered raw materials obtained in the step S1 are mixed with anhydrous ethanol, are pressed into a green body, are dried, are sintered, are naturally cooled, and beta-C2S is obtained. Compared with the prior art, trace heavy metals Cr2O3 and ZnO are used as the crystal structure regulator to regulate the beta-C2S crystal structure, so that sintering at a lower temperature, higher reactivity, reduced calcination energy consumption, reduced beta-C2S cost and the cooling mode of relatively rapid cooling in the furnace are realized, the method is safer, has very important practical significance for industrial production and application of the beta-C2S, and provides technical support for low-carbon development of the silicate cement.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic materials, and in particular to a method for preparing a β-C2S crystal structure. Background Technology

[0002] With the increasing severity of global warming, the massive emissions of carbon dioxide have attracted widespread attention worldwide. To promote the transformation of the cement industry towards energy conservation and emission reduction, reducing the amount of limestone (calcium carbonate) used in the manufacture of silicate cement is an important research direction. Existing research shows that belite (β-C2S), the main mineral phase of silicate cement, consumes significantly less limestone compared to allite (C3S), and exhibits superior long-term performance and lower early-stage heat of hydration. High-belite cement is one of the important technological pathways for the low-carbon development of silicate cement. However, compared to allite (C3S), β-C2S has relatively lower reactivity. How to regulate the crystal structure of β-C2S to enhance its reactivity has become a key research focus.

[0003] Currently, B2O3 is used as a mineralizing agent to prepare β-C2S. The preparation temperature is generally between 1350-1450℃, and the sintering is carried out by rapid cooling, which is not only costly, but also difficult to achieve in future large-scale industrial production applications.

[0004] Chinese patent CN202010197650.5 discloses an activation modification method for γ-C2S, which includes the following steps: 1) mixing calcium and silicon raw materials at a calcium-silicon molar ratio of 2:1, then adding a metal ion compound, ball milling and mixing to obtain a sintering raw material; 2) mixing the sintering raw material with 10% alcohol, pressing it into a green body, drying it, sintering it, and naturally cooling it to obtain metal ion-doped γ-C2S. However, the sintering temperature of this patent is 1400-1500℃, and the cost required to prepare metal ion-doped γ-C2S is relatively high. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of high preparation temperature, high cost, and dangerous cooling methods in existing β-C2S preparation methods by providing a method for preparing β-C2S crystal structures. This invention utilizes trace amounts of heavy metals Cr2O3 and ZnO as crystal structure modifiers to regulate the β-C2S crystal structure, achieving lower firing temperatures, higher reactivity, reduced calcination energy consumption, and lower β-C2S costs. Furthermore, the furnace cooling method is safer than rapid cooling, which has significant practical implications for the industrial production of β-C2S and provides technical support for the low-carbon development of silicate cement.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a β-C2S crystal structure, the specific steps of which are as follows:

[0008] S1. Mix calcium raw materials, silicon raw materials and crystal structure regulators according to a calcium-silicon molar ratio of 2:1 to obtain sintering raw materials. The crystal structure regulators include Cr2O3 and ZnO.

[0009] S2. The calcination raw material obtained in step S1 is mixed with anhydrous ethanol, pressed into a green body, dried, sintered, and naturally cooled to obtain β-C2S.

[0010] Furthermore, in step S1, the calcium raw material is analytical grade Ca(OH)2.

[0011] Furthermore, in step S1, the silicon raw material is analytical grade SiO2.

[0012] Further, in step S1, calcium raw materials, silicon raw materials, and crystal structure modifiers are mixed in a ball mill.

[0013] Further, in step S1, the amount of the crystal structure regulator is 0.5-2% of the total mass of the calcium and silicon raw materials.

[0014] Furthermore, in step S2, the mass fraction of the anhydrous ethanol is 10%.

[0015] Furthermore, in step S2, the drying temperature is 60-105℃.

[0016] Furthermore, in step S2, the molding pressure range of the pressed blank is 3-10 MPa, preferably 6 MPa.

[0017] Further, in step S2, the sintering process is as follows: heating to 1150-1350℃ at a heating rate of 10℃ / min, holding at that temperature for 3 hours, and then cooling in the furnace.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. This invention obtains β-C2S by using Cr2O3 and ZnO crystal structure regulators. The prepared β-C2S is mainly composed of β-C2S, and also includes a small amount of byproducts such as γ-C2S and C3S2. β-C2S is a calcium silicate mineral that not only has high carbonization activity, but also good hydration properties.

[0020] 2. This invention uses Cr2O3 and ZnO as crystal structure regulators to regulate the crystal structure of β-C2S, thereby reducing the preparation temperature of β-C2S and the production cost of β-C2S. Furthermore, β-C2S can be obtained by furnace cooling, which improves the production safety of β-C2S. This invention has very important practical significance for the industrial production and application of carbonization hardening cementitious materials.

[0021] 3. The main raw material of this invention is analytical grade Ca(OH)2, the silicon raw material is analytical grade SiO2, and the crystal structure regulator is Cr2O3 and ZnO. The raw materials are readily available and inexpensive.

[0022] 4. Compared with the prior art, the innovation of this invention is to use Cr2O3 and ZnO as crystal structure regulators to regulate the crystal structure of β-C2S, which can prepare β-C2S with 92% and 80% purity respectively at 1150℃. The innovation and improvement of this invention is to achieve lower temperature firing, higher hydration reaction activity, and reduce the cost of β-C2S. Attached Figure Description

[0023] Figure 1 The XRD patterns of β-C2S after Cr2O3 regulation in Examples 1-3 and Comparative Example 1 of this invention;

[0024] Figure 2 The results of TOPAS full spectrum fitting analysis of XRD of β-C2S after Cr2O3 regulation in Examples 1-3 and Comparative Example 1 of this invention;

[0025] Figure 3 The XRD patterns of β-C2S after ZnO regulation in Examples 4-6 and Comparative Example 2 of this invention;

[0026] Figure 4 The results are TOPAS full-spectrum fitting analysis results of XRD of β-C2S after ZnO regulation in Examples 4-6 and Comparative Example 2 of this invention. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0028] A method for preparing a β-C2S crystal structure, the specific steps of which are as follows:

[0029] S1. Mix calcium raw materials, silicon raw materials and crystal structure regulators according to a calcium-silicon molar ratio of 2:1 to obtain sintering raw materials. The crystal structure regulators include Cr2O3 and ZnO.

[0030] S2. The calcination raw material obtained in step S1 is mixed with anhydrous ethanol, pressed into a green body, dried, sintered, and naturally cooled to obtain β-C2S.

[0031] Furthermore, in step S1, the calcium raw material is analytical grade Ca(OH)2.

[0032] Furthermore, in step S1, the silicon raw material is analytical grade SiO2.

[0033] Further, in step S1, calcium raw materials, silicon raw materials, and crystal structure modifiers are mixed in a ball mill.

[0034] Further, in step S1, the amount of the crystal structure regulator is 0.5-2% of the total mass of the calcium and silicon raw materials.

[0035] Furthermore, in step S2, the mass fraction of the anhydrous ethanol is 10%.

[0036] Furthermore, in step S2, the drying temperature is 60-105℃.

[0037] Furthermore, in step S2, the molding pressure range of the pressed blank is 3-10 MPa, preferably 6 MPa.

[0038] Further, in step S2, the sintering process is as follows: heating to 1150-1350℃ at a heating rate of 10℃ / min, holding at that temperature for 3 hours, and then cooling in the furnace.

[0039] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0040] Example 1

[0041] A method for preparing a β-C2S crystal structure, the specific steps of which are as follows:

[0042] 1) According to the calcium-silicon molar ratio of 2:1, analytical grade Ca(OH)2, SiO2 and crystal structure regulator Cr2O3 were put into a ball mill and ball-milled for 3 hours to obtain calcined raw materials, wherein the amount of crystal structure regulator was 0.5%;

[0043] 2) After the calcined raw material is mixed evenly with 10% anhydrous ethanol, it is pressed into a green body under a molding pressure of 6 MPa. Then, it is thoroughly dried at 60°C. Subsequently, the dried green body is placed in a high-temperature furnace and heated to 1350°C at a heating rate of 10°C / min. It is held at this temperature for 3 hours and then naturally cooled to room temperature with the furnace to obtain β-C2S.

[0044] The β-C2S in this embodiment was ground, sieved, and then subjected to XRD testing. The test results are as follows: Figure 1 As shown, the β-C2S samples were also subjected to standard curing after casting. The compressive strength of β-C2S after 3 days of standard curing was 10 MPa, and the compressive strength of β-C2S after 28 days of standard curing was 43 MPa.

[0045] Example 2

[0046] A method for preparing a β-C2S crystal structure, the specific steps of which are as follows:

[0047] 1) According to the calcium-silicon molar ratio of 2:1, analytical grade Ca(OH)2, SiO2 and crystal structure regulator Cr2O3 were put into a ball mill and ball-milled for 3 hours to obtain calcined raw materials, wherein the amount of crystal structure regulator was 0.5%;

[0048] 2) After the calcining raw material is mixed evenly with 10% anhydrous ethanol, it is pressed into a green body under a molding pressure of 6 MPa. Then, it is thoroughly dried at 60°C. Subsequently, the dried green body is placed in a high-temperature furnace and heated to 1250°C at a heating rate of 10°C / min. It is held at this temperature for 3 hours and then naturally cooled to room temperature with the furnace to obtain β-C2S.

[0049] The β-C2S in this embodiment was ground, sieved, and then subjected to XRD testing. The test results are as follows: Figure 1 As shown in the figure. Simultaneously, the β-C2S samples were subjected to standard curing. After 3 days of standard curing, the compressive strength of β-C2S was 8 MPa, and after 28 days of standard curing, the compressive strength was 32 MPa.

[0050] Example 3

[0051] A method for preparing a β-C2S crystal structure, the specific steps of which are as follows:

[0052] 1) According to the calcium-silicon molar ratio of 2:1, analytical grade Ca(OH)2, SiO2 and crystal structure regulator Cr2O3 were put into a ball mill and ball-milled for 3 hours to obtain calcined raw materials, wherein the amount of crystal structure regulator was 0.5%;

[0053] 2) After the calcining raw material is mixed evenly with 10% anhydrous ethanol, it is pressed into a green body under a molding pressure of 6 MPa. Then, it is fully dried at 60°C. Subsequently, the dried green body is placed in a high-temperature furnace and heated to 1150°C at a heating rate of 10°C / min. It is held at this temperature for 3 hours and then naturally cooled to room temperature with the furnace to obtain β-C2S.

[0054] The β-C2S in this embodiment was ground, sieved, and then subjected to XRD testing. The test results are as follows: Figure 1As shown in the figure. Simultaneously, the β-C2S samples were subjected to standard curing. After 3 days of standard curing, the compressive strength of β-C2S was 9 MPa, and after 28 days of standard curing, the compressive strength was 43 MPa.

[0055] Example 4

[0056] A method for preparing a β-C2S crystal structure, the specific steps of which are as follows:

[0057] 1) According to the calcium-silicon molar ratio of 2:1, analytical grade Ca(OH)2, SiO2 and crystal structure regulator ZnO were put into a ball mill and ball-milled for 3 hours to obtain calcined raw materials, wherein the amount of crystal structure regulator was 0.5%;

[0058] 2) After the calcining raw material is mixed evenly with 10% anhydrous ethanol, it is pressed into a green body under a molding pressure of 6 MPa. Then, it is fully dried at 60°C. Subsequently, the dried green body is placed in a high-temperature furnace and heated to 1150°C at a heating rate of 10°C / min. It is held at this temperature for 3 hours and then naturally cooled to room temperature with the furnace to obtain β-C2S.

[0059] The β-C2S in this embodiment was ground, sieved, and then subjected to XRD testing. The test results are as follows: Figure 3 As shown, the β-C2S samples were also subjected to standard curing after casting. The compressive strength of β-C2S after 3 days of standard curing was 8 MPa, and the compressive strength of β-C2S after 28 days of standard curing was 34 MPa.

[0060] Example 5

[0061] A method for preparing a β-C2S crystal structure, the specific steps of which are as follows:

[0062] 1) According to the calcium-silicon molar ratio of 2:1, analytical grade Ca(OH)2, SiO2 and crystal structure regulator ZnO were put into a ball mill and ball-milled for 3 hours to obtain calcined raw materials, wherein the amount of crystal structure regulator was 1.5%;

[0063] 2) After the calcining raw material is mixed evenly with 10% anhydrous ethanol, it is pressed into a green body under a molding pressure of 6 MPa. Then, it is fully dried at 60°C. Subsequently, the dried green body is placed in a high-temperature furnace and heated to 1150°C at a heating rate of 10°C / min. It is held at this temperature for 3 hours and then naturally cooled to room temperature with the furnace to obtain β-C2S.

[0064] The β-C2S in this embodiment was ground, sieved, and then subjected to XRD testing. The test results are as follows: Figure 3As shown in the figure. Simultaneously, the β-C2S samples were subjected to standard curing. After 3 days of standard curing, the compressive strength of β-C2S was 6 MPa, and after 28 days of standard curing, the compressive strength was 25 MPa.

[0065] Example 6

[0066] A method for preparing a β-C2S crystal structure, the specific steps of which are as follows:

[0067] 1) According to the calcium-silicon molar ratio of 2:1, analytical grade Ca(OH)2, SiO2 and crystal structure regulator ZnO were put into a ball mill and ball-milled for 3 hours to obtain calcined raw materials, wherein the amount of crystal structure regulator was 2%;

[0068] 2) After the calcining raw material is mixed evenly with 10% anhydrous ethanol, it is pressed into a green body under a molding pressure of 6 MPa. Then, it is fully dried at 60°C. Subsequently, the dried green body is placed in a high-temperature furnace and heated to 1150°C at a heating rate of 10°C / min. It is held at this temperature for 3 hours and then naturally cooled to room temperature with the furnace to obtain β-C2S.

[0069] The β-C2S in this embodiment was ground, sieved, and then subjected to XRD testing. The test results are as follows: Figure 3 As shown in the figure. Simultaneously, the β-C2S samples were subjected to standard curing. After 3 days of standard curing, the compressive strength of β-C2S was 7 MPa, and after 28 days of standard curing, the compressive strength was 27 MPa.

[0070] Comparative Example 1

[0071] A method for preparing a β-C2S crystal structure, the specific steps of which are as follows:

[0072] 1) According to the calcium-silicon molar ratio of 2:1, analytical grade Ca(OH)2 and SiO2 were put into a ball mill and ball-milled for 3 hours to obtain the calcined raw material;

[0073] 2) After the calcining raw material is mixed evenly with 10% anhydrous ethanol, it is pressed into a green body under a molding pressure of 6MPa. Then, it is fully dried at 60℃. Subsequently, the dried green body is placed in a high-temperature furnace and heated to 1350℃ at a heating rate of 10℃ / min. It is held at this temperature for 3 hours and then naturally cooled to room temperature with the furnace to obtain clinker containing β-C2S.

[0074] The clinker in this embodiment has self-pulverizing properties and can be directly sieved and then subjected to XRD testing. The test results are as follows: Figure 1 As shown, the clinker samples were subjected to standard curing after casting. The compressive strength of the clinker after 3 days of standard curing was 1 MPa, and the compressive strength of β-C2S after 28 days of standard curing was 5 MPa.

[0075] Comparative Example 2

[0076] A method for preparing a β-C2S crystal structure, the specific steps of which are as follows:

[0077] 1) According to the calcium-silicon molar ratio of 2:1, analytical grade Ca(OH)2 and SiO2 were put into a ball mill and ball-milled for 3 hours to obtain the calcined raw material;

[0078] 2) After the calcining raw material is mixed evenly with 10% anhydrous ethanol, it is pressed into a green body under a molding pressure of 6MPa. Then, it is fully dried at 60℃. Subsequently, the dried green body is placed in a high-temperature furnace and heated to 1150℃ at a heating rate of 10℃ / min. It is held at this temperature for 3 hours and then naturally cooled to room temperature with the furnace to obtain clinker containing β-C2S.

[0079] The β-C2S in this embodiment was ground, sieved, and then subjected to XRD testing. The test results are as follows: Figure 3 As shown in the figure. Simultaneously, the β-C2S samples were subjected to standard curing. After 3 days of standard curing, the compressive strength of β-C2S was 6 MPa, and after 28 days of standard curing, the compressive strength was 24 MPa.

[0080] Compared to Comparative Example 1, the compressive strength of β-C2S in Examples 1-3 after 28 days of standard curing was 8.6, 7.8, and 8.6 times that of β-C2S in Example 1 after 28 days of standard curing, respectively. Using 0.5% Cr2O3 as a lattice modifier, β-C2S with a purity as high as 92% could be prepared at 1150℃. The compressive strength of the β-C2S samples after 28 days of standard curing after casting exceeded 42.5 MPa. Compared to Comparative Example 2, the compressive strength of β-C2S in Examples 4-6 after 28 days of standard curing was higher than that of β-C2S in Comparative Example 2. Using 0.5% ZnO as a lattice modifier, β-C2S with a purity of 80% could be prepared at 1150℃. The compressive strength of the β-C2S samples after 28 days of standard curing after casting exceeded 32.5 MPa.

[0081] The preparation of β-C2S uses B2O3 as a mineralizing agent, and the preparation temperature is generally between 1350-1450℃. In Example 3 of this method, 0.5% Cr2O3 is used as a lattice modifier, and β-C2S with a purity of up to 92% can be prepared at a temperature of 1150℃. The preparation temperature is reduced by 200-300℃, thus reducing the production cost of β-C2S.

[0082] In this invention, Cr2O3 and ZnO crystal structure regulators are used to regulate the crystal structure of β-C2S, and high-purity β-C2S with good hydration activity is obtained at low temperature. After molding, its hydration strength can reach the 42.5 grade cement strength standard.

[0083] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for producing a β-C2S crystal structure, characterized by, The specific steps are as follows: S1, according to the calcium-silicon molar ratio of 2:1, the calcareous raw material, silicon raw material and crystal structure regulator are mixed to obtain the sintered raw material, the crystal structure regulator includes Cr2O3 or ZnO, the amount of the crystal structure regulator is 0.5% of the total mass of the calcareous raw material and the silicon raw material; S2, the sintered raw material obtained in step S1 is mixed with anhydrous ethanol, pressed into a green body, dried, sintered, and naturally cooled to obtain β-C2S; The sintering process of the sintering is as follows: the temperature is raised to 1150℃ at a heating rate of 10℃ / min, and the temperature is kept for 3h, and the furnace is cooled.

2. The method for preparing a β-C2S crystal structure according to claim 1, characterized in that, In step S1, the calcareous raw material is analytical pure Ca(OH)2.

3. The method of claim 1, wherein the β-C2S crystal structure is prepared by adding 0.1 to 0.5 wt% of the compound of formula (I) to the mixture of the raw materials. In step S1, the silicon raw material is analytical pure SiO2.

4. The method of claim 1, wherein the β-C2S crystal structure is prepared by adding 0.1 to 0.5 wt% of the compound of formula (I) to the mixture of the raw materials. In step S1, the calcareous raw material, silicon raw material and crystal structure regulator are put into a ball mill for mixing.

5. The method of claim 1, wherein the β-C2S crystal structure is prepared by adding 0.1-0.5 wt% of the compound of formula (I) to the mixture of calcium oxide and silicon dioxide. In step S2, the mass fraction of the anhydrous ethanol is 10%.

6. The method for preparing a β-C2S crystal structure according to claim 1, characterized in that, In step S2, the drying temperature of the drying is 60-105℃.

7. The method for preparing a β-C2S crystal structure according to claim 1, characterized in that, In step S2, the forming pressure range of the pressing into a green body is 3-10 MPa.

8. The method of claim 7, wherein the β-C2S crystal structure is prepared by the following steps of: The forming pressure of the pressing into a green body is 6 MPa. ​

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