A low-carbon cementitious material and its preparation method

Abstract

The present invention discloses a low-carbon cementitious material and a preparation method thereof, which relates to the technical field of metallurgy. The method includes fully mixing industrial solid waste with metal alkaline hydroxides, silicon oxides, and pulverized coal in a certain proportion to obtain a mixed material; calcining the mixed material at a certain temperature and then grinding it to obtain the calcined industrial solid waste; wherein the calcination temperature is 300-1000 °C and the calcination time is 1-8 hours; adding an alkali activator to the calcined industrial solid waste, fully mixing it, and then performing hydration curing to obtain a high-strength low-carbon cementitious material. The preparation method of the low-carbon cementitious material of the present invention adopts the synergistic heat treatment of multiple industrial solid wastes. By the method of synergistic heat treatment of multiple solid wastes and additives, the latent activity of the solid wastes is greatly stimulated, and the synergistic cementitious effect among the solid wastes is exerted. Under the action of a conventional alkali activator and low-temperature calcination, the latent activity of the solid wastes can be greatly stimulated to obtain a high-strength low-carbon cementitious material.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical technology, and particularly to a low-carbon cementitious material and a preparation method thereof. Background Art

[0002] A large amount of solid waste is generated in the production process of the metallurgical industry, which has disadvantages such as poor activity and easy swelling when exposed to water. At present, there is no effective treatment method. The common practice of enterprises is to stack it or use a small amount as a cement filler, but the blending ratio in cement is low, and the issuance of the new national standard "Common Portland Cement" (GB175-2023) has clearly restricted the application of industrial solid waste in the cement field. The low-carbon cementitious material has the characteristics of environmental protection, and all the industrial solid waste is utilized, which can replace cement concrete as a structural building material. Research shows that the problems of low-carbon cementitious materials mainly focus on how to efficiently exert the synergistic effect among solid wastes. Regarding the above problems, scholars have carried out a large number of studies. Most of the studies focus on the influence of various reaction parameters such as the type and dosage of alkali activators, mechanical activation time and method, the type of chemical activators and pH on the activity of the materials. However, there are still problems such as single activation means, poor activity excitation effect, low strength, high process implementation cost or low material added value, and engineering application has not been realized. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a preparation method of a low-carbon cementitious material. The method uses a variety of industrial solid wastes as raw materials, and through the synergistic heat treatment of various solid wastes and additives, the synergistic cementitious effect among solid wastes is exerted, so as to obtain a high-strength low-carbon cementitious material.

[0004] The present invention adopts the following technical solutions:

[0005] A preparation method of a low-carbon cementitious material, the method comprising:

[0006] Fully mixing industrial solid waste with metal alkaline hydroxide, silicon oxide, and pulverized coal in a certain proportion to obtain a mixed material;

[0007] Roasting the mixed material at a certain temperature and then grinding to obtain roasted industrial solid waste; wherein the roasting temperature is 300-1000°C and the roasting time is 1-8 hours;

[0008] Adding an alkali activator to the roasted industrial solid waste, fully mixing and then curing by hydration to obtain a high-strength low-carbon cementitious material;

[0009] Wherein, the dosage of the metal alkaline hydroxide in the mixed material is 5%-30%; the dosage of the silicon oxide is 1%-10%; the dosage of the pulverized coal is 1%-5%; the rest is industrial solid waste;

[0010] The dosage of the alkali activator and the water-cement ratio of the industrial solid waste are 0.2 to 0.5.

[0011] Among them, the industrial solid waste is the solid waste generated during the industrial production process, and the industrial solid waste includes CaO, SiO 2 and Al 2 O 3 . Among them, the mass percentage content of CaO is not less than 10%, the mass percentage content of SiO 2 is not less than 30%, and the mass percentage content of Al 2 O 3 is not less than 20%;

[0012] And the mass percentage content of Fe 2 O 3 in the industrial solid waste is not more than 5%.

[0013] Among them, the mass percentage content of CaO in the industrial solid waste is 10 to 20%, the mass percentage content of SiO 2 is 30 to 35%, and the mass percentage content of Al 2 O 3 in the industrial solid waste is 25 to 31%. Preferably, the mass percentage content of CaO in the industrial solid waste is 11 to 20%, the mass percentage content of SiO 2 is 30 to 33%, and the mass percentage content of Al 2 O 3 in the industrial solid waste is 25 to 31%. More preferably, the closer the mass ratio of SiO 2 and Al 2 O 3 is to 1, the better. Preferably, the mass ratio of SiO 2 and Al 2 O 3 is 1.08 to 1.06.

[0014] Among them, the water content of the industrial solid waste is below 10wt%;

[0015] And / or, the specific surface area of the industrial solid waste is greater than 200m 2 / kg.

[0016] Among them, the metal alkaline hydroxide is one or more of KOH, NaOH, BaOH 2 , Ca(OH) 2 , Mg(OH) 2 , Zn(OH) 2 or Sr(OH) 2 .

[0017] Among them, the oxide of silicon is one or a mixture of several of silicon monoxide, silicon dioxide or double silicate.

[0018] Among them, the particle size range of the oxide of silicon is 1 to 100 nm.

[0019] Among them, the diameter range of the pulverized coal particles is 0 to 1000 μm, and the carbon content > 80%;

[0020] And / or, the particle size of the industrial solid waste is 40 to 150 microns.

[0021] Among them, the alkali activator is a sodium silicate solution, and the modulus range is 0.5 to 3.

[0022] Among them, the curing process of the low-carbon cementitious material is: temperature 10 to 30 °C, humidity 80 to 100%, and curing time 3 to 28 days.

[0023] A low-carbon cementitious material is prepared by the above method.

[0024] The beneficial effects of the present invention are:

[0025] The preparation method of the low-carbon cementitious material of the present invention adopts the co-thermal treatment of multiple industrial solid wastes. By the method of co-thermal treatment of various solid wastes and additives, the latent activity of the solid wastes is greatly stimulated. Different types and mixing ratios of solid wastes are selected to exert the synergistic cementitious effect between the solid wastes. Under the action of conventional alkali activators and low-temperature roasting, the latent activity of the solid wastes can be greatly stimulated to obtain a high-strength low-carbon cementitious material. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the compressive strength results of the low-carbon cementitious materials prepared in Examples 1 to 4.

[0027] Figure 2 It is a schematic diagram of the compressive strength results of the low-carbon cementitious materials prepared in Example 1, Comparative Example 1, Comparative Example 2, Example 5 and Example 6. Detailed Embodiments

[0028] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] The embodiments of the present invention will be described in detail below. The embodiments are implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0030] Example 1

[0031] In this example, two kinds of industrial solid wastes are selected to prepare a low-carbon cementitious material.

[0032] Among them, the composition of industrial solid waste 1 is: CaO 35wt%, SiO 2 25wt%, Al 2 O 3 15wt%, SO 3 5wt%, Fe 2 O 3 3 wt%, Na 2 O 2%; the composition of industrial solid waste 2 is: CaO 5wt%, SiO 2 35wt%, Al 2 O 3 35wt%, SO 3 5wt%, Fe 2 O 3 5 wt%.

[0033] Industrial solid waste 1 and industrial solid waste 2 are dried at 100°C for 24 hours, then ground and passed through a 120-mesh sieve. After industrial solid waste 1 and industrial solid waste 2 are fully mixed at a ratio of 1:1, 5% Ba(OH) 2 , 10% silicon oxide and 5% pulverized coal are added. After being fully mixed with the above industrial solid waste, it is placed in a high-temperature furnace for heat treatment. The high-temperature furnace is heated to 700°C at a rate of 5°C / min, isothermally maintained for 2 hours, and then cooled with the furnace. After taking out the sample and grinding, the calcined industrial solid waste with a specific surface area of 300 cm 2 / g is obtained; the sodium silicate alkali activator with a modulus of 1 is added to the calcined industrial solid waste according to a water-cement ratio of 0.3. After being fully mixed, the above materials are placed in a mold of 4×4×4 cm 3 , and cured in a standard curing box for 28 days to obtain a low-carbon cementitious material.

[0034] Example 2

[0035] It is basically the same as the preparation method of Example 1, except that the ratio of industrial solid waste 1 to industrial solid waste 2 is reduced from 1:1 to 1:2.

[0036] Example 3

[0037] It is basically the same as the preparation method of Example 1, except that the ratio of industrial solid waste 1 to industrial solid waste 2 is reduced from 1:1 to 1:3.

[0038] Example 4

[0039] It is basically the same as the preparation method of Example 1, except that the ratio of industrial solid waste 1 to industrial solid waste 2 is reduced from 1:1 to 1:4.

[0040] Comparative Example 1

[0041] It is basically the same as the preparation method of Example 1, except that the ratios of the added Ba(OH) 2 , silicon oxide, and pulverized coal are all reduced from 5%, 10%, and 5% to 0%.

[0042] Example 5

[0043] It is basically the same as the preparation method of Example 1, except that the ratios of the added Ba(OH) 2 , silicon oxide, and pulverized coal are adjusted to 10%, 6%, and 2%. The compressive strengths of the low-carbon cementitious materials prepared in Examples 1, 2, 3, 4, 5, and Comparative Example 1 are as Figure 1 and Figure 2 shown. It can be seen from Figure 1 that as the ratio of industrial solid waste 1 to industrial solid waste 2 decreases, the compressive strength of the low-carbon cementitious material shows a downward trend. When the ratio is 1:4, the compressive strength reaches a maximum of 97.1 MPa, far exceeding the strength range of C80 ultra-high-strength cement concrete. It can be seen from Figure 2 that compared with the low-carbon cementitious material added with Ba(OH) 2 , silicon oxide, and pulverized coal, the low-carbon cementitious material without additives has a lower compressive strength.

[0044] Example 6

[0045] The preparation process of this example is the same as that of Example 1.

[0046] The difference is that the ratios of the added Ba(OH) 2 , silicon oxide, and pulverized coal are adjusted to 30%, 1%, and 1%; at the same time, the calcination temperature is adjusted to 300 °C and the calcination time is 8 h. After measurement, the compressive strength of this example is 63.4 MPa.

[0047] Example 7

[0048] The preparation process of this example is the same as that of Example 1.

[0049] The difference is that the calcination temperature is adjusted to 1000 °C and the calcination time is 1 h.

[0050] Comparative Example 2

[0051] The preparation process of this embodiment is the same as that of Embodiment 1.

[0052] The difference lies in that the content of Fe 2 O 3 in the industrial solid waste is 10%. After measurement, the compressive strength of the sample prepared in Comparative Example 2 is 30.5 Mpa, which is much lower than 65.8 Mpa of Embodiment 1. It shows that the mass percentage content of Fe 2 O 3 in the industrial solid waste should not be too large, and the inventor believes it should not be greater than 5%.

[0053] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

[0054] The parts not elaborated in detail in the specification of the present invention belong to the well-known technology in the art. The above embodiments are provided only for the purpose of describing the present invention, rather than limiting the scope of the present invention. The scope of the present invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principle of the present invention shall be covered within the scope of the present invention.

Claims

1. A method for preparing a low-carbon gelling material, characterized in that: The method comprises: The industrial solid waste is fully mixed with metal alkaline hydroxide, silicon oxide and coal powder in a certain proportion to obtain a mixed material; The mixed material is roasted at a certain temperature and then ground to obtain roasted industrial solid waste; wherein the roasting temperature is 300-1000° C. and the roasting time is 1-8 hours; Adding an alkali activator to the calcined industrial solid waste, fully mixing and hydrating and curing, to obtain a high-strength low-carbon cementitious material; the alkali activator is a sodium silicate solution; Among them, the amount of the metal alkaline hydroxide added to the mixed material is 5% to 30%; the amount of the silicon oxide added is 1% to 10%; the amount of the coal powder added is 1% to 5%; and the rest is industrial solid waste; The amount of the alkali activator added and the water-cement ratio of the industrial solid waste are 0.2-0.5; The industrial solid waste is solid waste generated in the industrial production process, and the industrial solid waste includes CaO, SiO2 and Al2O3, wherein the mass percentage of CaO is not less than 10%, the mass percentage of SiO2 is not less than 30%, and the mass percentage of Al2O3 is not less than 20%; and the mass ratio of SiO2 to Al2O3 in the industrial solid waste is 1.06~1.08; and the mass percentage of Fe2O3 in the industrial solid waste is not more than 5%.

2. The method for preparing a low-carbon cementitious material according to claim 1, characterized in that: The mass percentage of CaO in the industrial solid waste is 10-20%, the mass percentage of SiO2 is 30-35%, and the mass percentage of Al2O3 in the industrial solid waste is 25-31%.

3. The method for preparing a low-carbon cementitious material according to claim 1, characterized in that: The water content of the industrial solid waste is below 10wt%; And / or, the specific surface area of ​​the industrial solid waste is greater than 200m 2 / kg.

4. The method for preparing a low-carbon cementitious material according to claim 1, characterized in that: The metal alkaline hydroxide is one or more of KOH, NaOH, BaOH2, Ca(OH)2, Mg(OH)2, Zn(OH)2 or Sr(OH)2.

5. The method for preparing a low-carbon cementitious material according to claim 1, characterized in that: The silicon oxide is one of silicon monoxide, silicon dioxide or bisilicate or a mixture of several thereof.

6. The method for preparing a low-carbon cementitious material according to claim 1, characterized in that: The particle size of the silicon oxide is in the range of 1 to 100 nm.

7. The method for preparing a low-carbon cementitious material according to claim 1, characterized in that: The coal powder particle diameter range is greater than 0 and less than or equal to 1000 μm, and the carbon content is greater than 80%; And / or, the particle size of the industrial solid waste is 40 to 150 microns.

8. The method for preparing a low-carbon cementitious material according to claim 1, characterized in that: The modulus of the sodium silicate solution ranges from 0.5 to 3.

9. The method for preparing a low-carbon cementitious material according to any one of claims 1 to 8, characterized in that: The curing process of the low-carbon cementitious material is as follows: temperature 10-30° C., humidity 80-100%, and curing time 3-28 days.

10. A low-carbon cementitious material, characterized in that: The method is prepared by any one of claims 1 to 9.

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