Alkali efflorescence prevention aluminate cement combined aluminum-silicon series refractory castable and preparation method thereof

Abstract

The invention relates to the technical field of castable, in particular to an alkali efflorescence prevention aluminate cement combined aluminum-silicon series refractory castable and a preparation method thereof. The raw materials of the refractory castable comprise a basic raw material and an additive, the additive comprises an alkali inhibitor and a water reducing agent; the alkali inhibitor comprises mordenite or nano calcium carbonate; the basic raw material is prepared from the following raw materials in percentage by mass: 65 to 75 percent of aluminum-silicon refractory particles, 10 to 13 percent of aluminum-silicon refractory fine powder, 5 to 8 percent of alpha-Al2O3 micro powder, 6 to 10 percent of SiO2 micro powder and 4 percent of pure calcium aluminate cement; the water reducing agent accounts for 0.1-0.3 wt% of the basic raw materials; the mordenite accounts for 0.3-0.5 wt% of the basic raw materials; the nano calcium carbonate accounts for 0-1wt% of the basic raw materials.

Description

Technical Field

[0001] The invention relates to the technical field of castables, in particular to an anti-reflux aluminate cement combined aluminum-silicon refractory castable and a preparation method thereof. Background Art

[0002] Refractory materials are used in industries such as steel, glass, cement, and petrochemicals. Among them, silicon-aluminum refractories have attracted considerable attention due to their advantages: First, they maintain structural stability even in high-temperature environments and are less susceptible to thermal deformation or shrinkage; second, they are effectively resistant to corrosion by strong acids and alkalis; and third, they have low thermal conductivity, effectively preventing heat conduction.

[0003] However, at present, the alkali backflow phenomenon is easy to occur in the preparation process of silicon-aluminum refractory materials. It is mainly manifested in the formation of white alkali metal salts on the surface of the material, which leads to surface powdering and weakening of structural strength. It not only affects the appearance of the material, but also reduces the performance and life of the material in actual application. The root cause is the CAH generated during the hydration process of calcium aluminate cement (CAC). 10 Unstable hydration products such as alkali metal ions easily react with carbon dioxide and alkali metal ions in the air to form soluble salts, which not only affect the early strength development of the castable, but also affect the long-term stability and durability of the material.

[0004] In existing technologies, some solutions attempt to address the alkali reaction problem through surface treatment and optimized formulations. Patent CN104446655B uses phosphoric acid solution, sulfuric acid solution, and alumina powder to prepare a release agent to prevent the reaction of alkali metal salts with carbon dioxide in the air, thereby suppressing the alkali reaction. However, the preparation and application process of the release agent are relatively complex, increasing the difficulty and hindering large-scale application. Patent CN115304384B optimizes the formulation by introducing raw materials such as magnesium-aluminum hydrotalcite powder and silica powder. However, the addition of magnesium-aluminum hydrotalcite has the potential to affect the high-temperature performance of the castable, requiring further formulation optimization.

[0005] Therefore, it is of great significance to solve the above problems and obtain an anti-alkali aluminate cement combined with aluminum-silicon refractory castable. Summary of the Invention

[0006] The object of the present invention is to provide an alkali-resistant aluminate cement combined with aluminum-silicon refractory castable and a preparation method thereof, so as to solve the problems raised in the prior art.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] An alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable, wherein the raw materials of the refractory castable include basic raw materials and admixtures; the admixtures include an alkali inhibitor and a water reducer; the alkali inhibitor includes mordenite or nano-calcium carbonate;

[0009] The raw materials of the basic raw materials include the following mass components, calculated by mass percentage: 65-75% aluminum-silicon refractory particles, 10-13% aluminum-silicon refractory fine powder, 5-8% α-Al2O3 fine powder, 6-10% SiO2 fine powder, and 4% pure calcium aluminate cement.

[0010] More optimally, the water reducer accounts for 0.1 to 0.3 wt% of the basic raw material; the water reducer includes one or both of sodium tripolyphosphate and sodium hexametaphosphate.

[0011] In a further embodiment, the water reducer comprises sodium tripolyphosphate and sodium hexametaphosphate in a mass ratio of 1.5 to 2:1.

[0012] More optimally, the alkali inhibitor is mordenite, which accounts for 0.3-0.5 wt% of the basic raw material; and the particle size of the mordenite is ≤5.4 μm.

[0013] Among them, mordenite has a microporous structure, ultra-high specific surface area and strong ion adsorption capacity, which can inhibit the alkali backflow phenomenon through the dual mechanism of physical isolation and chemical adsorption and complexation. Firstly, it can complex Na + , K + , Ca 2 Alkali metal ions such as zeolite can regulate the ion concentration in the hydration process, promote the hydration reaction, and reduce the reaction with CO2 to form white alkali metal salts; secondly, during the normal to medium temperature curing stage, the highly active surface of mordenite acts as a nucleation site to promote the formation of flake hydration products C4AcH 11 Directed growth, replacing CAH which is easy to return to alkali 10 , improve the ability to resist alkali erosion; thirdly, the nano-scale dispersion characteristics of mordenite can fill the pores of the matrix, improve the density of the castable, close the pores, further reduce the penetration of air and water, and inhibit the alkali backflow phenomenon.

[0014] More optimally, the alkali inhibitor is nano-calcium carbonate, which accounts for 0-1 wt% of the basic raw material; and the particle size of the nano-calcium carbonate is ≤1 μm.

[0015] Among them, the addition of nano-calcium carbonate sintering helps to induce more flake hydration products C4AcH 11 The production of flake hydration product C4AcH 11 Has strong stability and can effectively fix Ca 2+It also blocks the migration path of alkali metal ions, promotes densification of the material matrix, isolates air exchange during the curing process, and effectively inhibits alkali reversion. Nano-CaCO3 decomposes at high temperatures to form CaO, providing more active sites and carbon sources, helping to form slender CA6 grains, optimizing the microstructure of the castable, and improving its high-temperature performance and corrosion resistance.

[0016] More optimally, the aluminum-silicon refractory particles include alumina and coke particles in a mass ratio of 1.5 to 2.5:1; the particle size of the aluminum-silicon refractory particles is 0.088 to 8 mm.

[0017] More optimally, the aluminum-silicon refractory fine powder includes alumina, kyanite, and mullite fine powders in a mass ratio of 1.5 to 2.5:1:1; the particle size of the aluminum-silicon refractory fine powder is ≤0.088 mm.

[0018] More optimally, the particle size of the α-Al2O3 fine powder is ≤5μm; the content of Al2O3 in the α-Al2O3 fine powder is ≥97wt%.

[0019] More optimally, the particle size of the SiO2 powder is ≤0.2 μm.

[0020] More optimally, the particle size of the pure calcium aluminate cement is 320-330 meshes; the content of Al2O3 in the pure calcium aluminate cement is ≥71wt%.

[0021] More optimally, a method for preparing an anti-reversion alkali aluminate cement combined with an aluminum-silicon refractory castable comprises the following steps:

[0022] Step 1: Mix aluminum-silicon refractory particles, aluminum-silicon refractory fine powder, α-Al2O3 fine powder, SiO2 fine powder, and pure calcium aluminate cement to obtain basic raw materials;

[0023] Step 2: Mix the alkali inhibitor and the water reducer to obtain an admixture;

[0024] Step 3: Mix the basic raw materials and admixtures to obtain refractory castables.

[0025] In a further scheme, the hydration reaction process of calcium aluminate cement is: CA+10H→CAH 10 The formation process of C2AH8 is: 2CA+11H→C2AH8; the formation process of lamellar hydration products is 3CA+Cc+17H→C4AcH 11 +2AH3.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] This scheme studies the characteristic hydrated phase CAH 10, C2AH8, C3AH6 and C4AcH 11 The stability under the action of alkali metal ions and CO2 reveals the mechanism of alkali reversion. By designing the raw materials of refractory castables with specific content, the composition of hydration products is optimized and the hydration phase CAH that is prone to alkali reversion is reduced. 10 The formation of the stable hydrated phase C4AcH 11 The content of the product is high, and the product has excellent properties such as high strength and resistance to alkali corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 is the pore size distribution diagram of samples with different nano-CaCO3 contents;

[0030] Figure 2 The pore volume distribution diagram of samples with different nano-CaCO3 contents;

[0031] Figure 3 The pore volume percentage distribution diagram of samples with different nano-CaCO3 contents;

[0032] Figure 4 is the X-ray diffraction pattern of the refractory castable of Example 6;

[0033] Figure 5 This is the refractory castable of Example 6 before being cured at a constant temperature of 15° C. for 9 days;

[0034] Figure 6 This is the refractory castable of Example 6 after being cured at a constant temperature of 15°C for 9 days. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] It should be noted that all raw material purchasing manufacturers involved in the present invention are not subject to any special restrictions and exemplarily include: in the following embodiments, the particle size of nano-calcium carbonate is 1 μm; the particle size of mordenite is 5.4 μm; the CAS number of sodium tripolyphosphate is 7758-29-4; the CAS number of sodium hexametaphosphate is 10124-56-8; the particle size of aluminum-silicon refractory particles is 4 mm; the particle size of aluminum-silicon refractory fine powder is 0.088 mm; the particle size of α-Al2O3 micropowder is 5 μm; the particle size of SiO2 micropowder is 0.2 μm; and the particle size of pure calcium aluminate cement is 330 mesh.

[0037] The following examples are particularly described:

[0038] (1) Alumina-silicon refractory particles include alumina and coke particles with a mass ratio of 2:1;

[0039] (2) Aluminum-silicon refractory fine powder includes alumina, kyanite, and mullite fine powder in a mass ratio of 2:1:1;

[0040] (3) The water reducer includes sodium tripolyphosphate and sodium hexametaphosphate in a mass ratio of 2:1.

[0041] Example 1: A method for preparing an alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable, comprising the following steps:

[0042] Step 1: Mix 70% of aluminum-silicon refractory particles, 15% of aluminum-silicon refractory fine powder, 5% of α-Al2O3 fine powder, 6% of SiO2 fine powder, and 4% of pure calcium aluminate cement to obtain a basic raw material;

[0043] Step 2: mixing an alkali inhibitor and a water reducer, wherein the water reducer accounts for 0.2 wt% of the basic raw material, and the alkali inhibitor is mordenite, which accounts for 0.3 wt% of the basic raw material; to obtain an admixture;

[0044] Step 3: Mix the basic raw materials and admixtures to obtain refractory castables.

[0045] Example 2: A method for preparing an alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable, comprising the following steps:

[0046] Step 1: Mix 70% of aluminum-silicon refractory particles, 12% of aluminum-silicon refractory fine powder, 6% of α-Al2O3 fine powder, 7% of SiO2 fine powder, and 4% of pure calcium aluminate cement to obtain a basic raw material;

[0047] Step 2: mixing an alkali inhibitor and a water reducer, wherein the water reducer accounts for 0.2 wt% of the basic raw material, and the alkali inhibitor is mordenite, which accounts for 0.4 wt% of the basic raw material; to obtain an admixture;

[0048] Step 3: Mix the basic raw materials and admixtures to obtain refractory castables.

[0049] Example 3: A method for preparing an alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable, comprising the following steps:

[0050] Step 1: 68% of aluminum-silicon refractory particles, 13% of aluminum-silicon refractory fine powder, 7% of α-Al2O3 fine powder, 8% of SiO2 fine powder, and 4% of pure calcium aluminate cement are mixed to obtain a basic raw material;

[0051] Step 2: mixing an alkali inhibitor and a water reducer, wherein the water reducer accounts for 0.2 wt% of the basic raw material, and the alkali inhibitor is mordenite, which accounts for 0.5 wt% of the basic raw material; to obtain an admixture;

[0052] Step 3: Mix the basic raw materials and admixtures to obtain refractory castables.

[0053] Example 4: A method for preparing an alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable, comprising the following steps:

[0054] Step 1: Mix 75% of aluminum-silicon refractory particles, 10% of aluminum-silicon refractory fine powder, 5% of α-Al2O3 fine powder, 6% of SiO2 fine powder, and 4% of pure calcium aluminate cement to obtain a basic raw material;

[0055] Step 2: Mix the basic raw materials and the water reducer, wherein the water reducer accounts for 0.2 wt % of the basic raw materials, to obtain a refractory castable.

[0056] Example 5: A method for preparing an alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable, comprising the following steps:

[0057] Step 1: Mix 71% of aluminum-silicon refractory particles, 12% of aluminum-silicon refractory fine powder, 6% of α-Al2O3 fine powder, 7% of SiO2 fine powder, and 4% of pure calcium aluminate cement to obtain a basic raw material;

[0058] Step 2: mixing an alkali inhibitor and a water reducer, wherein the water reducer accounts for 0.2 wt% of the basic raw material, and the alkali inhibitor is nano calcium carbonate, which accounts for 0.5 wt% of the basic raw material; to obtain an admixture;

[0059] Step 3: Mix the basic raw materials and admixtures to obtain refractory castables.

[0060] Example 6: A method for preparing an alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable, comprising the following steps:

[0061] Step 1: 68% of aluminum-silicon refractory particles, 13% of aluminum-silicon refractory fine powder, 7% of α-Al2O3 fine powder, 8% of SiO2 fine powder, and 4% of pure calcium aluminate cement are mixed to obtain a basic raw material;

[0062] Step 2: mixing an alkali inhibitor and a water reducer, wherein the water reducer accounts for 0.2 wt% of the basic raw material and the alkali inhibitor is nano calcium carbonate, which accounts for 1 wt% of the basic raw material; to obtain an admixture;

[0063] Step 3: Mix the basic raw materials and admixtures to obtain refractory castables.

[0064] Test experiment 1: (1) The refractory castables prepared in Examples 1 to 6 were stirred with water and formed, and then cured at a constant temperature of 15°C for 3 to 9 days. The surface was observed for alkali reversion, and the room temperature flexural strength and room temperature compressive strength were measured. The test results are shown in Table 1. (2) The refractory castable prepared in Example 6 was tested for room temperature compressive strength and alkali corrosion resistance, and the improvement ratio was calculated. The test results are shown in Table 2.

[0065] Table 1

[0066]

[0067] Table 2

[0068]

[0069] Result analysis: It can be seen from the data in Tables 1 and 2 that the refractory castables prepared by this scheme did not experience alkali reversion on the surface after adding water, stirring and molding, and then curing and placing. The room-temperature flexural strength, room-temperature compressive strength, and alkali corrosion resistance were all improved; among them, Examples 5 and 6 had the best performance.

[0070] Test experiment 2: (1) Using the same preparation process to produce different pore size distributions of nano-CaCO3, such as Figures 1 to 3 (2) X-ray diffraction pattern of the refractory castable of Test Example 6, as shown Figure 4 (3) Surface comparison of the refractory castable in Test Example 6 before and after curing at a constant temperature of 15°C for 9 days, as shown in FIG. Figures 5-6 As shown;

[0071] Result analysis: Figures 1 to 3 It can be seen that the number of micropores with a diameter range of 1 to 10 μm increases, and as the amount of calcium carbonate added increases to 1%, the cumulative intrusion curve moves to the right, the pore size increases, and the total intrusion amount also increases; Figure 4 It can be seen that nano calcium carbonate can promote the hydration of calcium aluminate cement and induce C4AcH 11 formed by Figures 5-6 It can be seen that adding 1% nano-calcium carbonate to the castable promotes the densification of the material matrix and effectively inhibits the occurrence of alkali reversion.

[0072] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. An alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable, characterized by: The raw materials of the refractory castable include basic raw materials and admixtures; the admixtures include alkali inhibitors and water reducers; the alkali inhibitors include mordenite or nano calcium carbonate; The raw materials of the basic raw materials include the following mass components, calculated by mass percentage: 65-75% aluminum-silicon refractory particles, 10-13% aluminum-silicon refractory fine powder, 5-8% α-Al2O3 fine powder, 6-10% SiO2 fine powder, and 4% pure calcium aluminate cement.

2. The alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable according to claim 1, characterized in that: The water reducer accounts for 0.1-0.3 wt% of the basic raw material; the water reducer comprises one or two of sodium tripolyphosphate and sodium hexametaphosphate.

3. The alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable according to claim 1, characterized in that: The alkali inhibitor is mordenite, which accounts for 0.3-0.5 wt% of the basic raw material; and the particle size of the mordenite is ≤5.4 μm.

4. The alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable according to claim 1, characterized in that: The alkali inhibitor is nano calcium carbonate, which accounts for 0-1 wt% of the basic raw material; and the particle size of the nano calcium carbonate is ≤1 μm.

5. The alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable according to claim 1, characterized in that: The aluminum-silicon refractory particles include alumina and coke particles in a mass ratio of 1.5 to 2.5:1; the particle size of the aluminum-silicon refractory particles is 0.088 to 8 mm.

6. The alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable according to claim 1, characterized in that: The aluminum-silicon refractory fine powder comprises alumina, kyanite and mullite fine powders in a mass ratio of 1.5 to 2.5:1:1; the particle size of the aluminum-silicon refractory fine powder is ≤0.088 mm.

7. The alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable according to claim 1, characterized in that: The particle size of the α-Al2O3 fine powder is ≤5 μm; the content of Al2O3 in the α-Al2O3 fine powder is ≥97 wt%.

8. The alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable according to claim 1, characterized in that: The particle size of the SiO2 fine powder is ≤0.2 μm.

9. The alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable according to claim 1, characterized in that: The particle size of the pure calcium aluminate cement is 320-330 meshes; the content of Al2O3 in the pure calcium aluminate cement is ≥71wt%.

10. The method for preparing an alkali-resistant aluminate cement-bonded aluminum-silicon refractory castable according to claim 9, characterized in that: The following steps are involved: Step 1: Mix aluminum-silicon refractory particles, aluminum-silicon refractory fine powder, α-Al2O3 fine powder, SiO2 fine powder, and pure calcium aluminate cement to obtain basic raw materials; Step 2: Mix the alkali inhibitor and the water reducer to obtain an admixture; Step 3: Mix the basic raw materials and admixtures to obtain refractory castables.

Images