Breathable sand mold for fused bricks and preparation method of breathable sand mold

Abstract

The invention relates to the technical field of refractory materials, in particular to a fused brick breathable sand mold and a preparation method thereof. Comprising the following components in percentage by weight: 90-96% of solid waste crude sand and 4-10% of diversified breathable particles. The diversified breathable particles comprise the following components in percentage by weight: 32%-36% of aluminum dihydrogen phosphate, 29%-33% of white granulated sugar and 35%-38% of calcium hydroxide. Wherein the particle size of the white granulated sugar is 0.5 mm to 1 mm. Wherein the particle size of the calcium hydroxide is 300 meshes, the aluminum dihydrogen phosphate is a solution, and the mass percentage content of the aluminum dihydrogen phosphate in the aluminum dihydrogen phosphate solution is 50%. The method effectively solves the problem of reutilization of the sand powder fine powder in the solid waste sand in the sand mold, and realizes efficient reuse and air permeability optimization of the fine powder through a solid waste fine powder regeneration and diversified air-permeable particle technology.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, and in particular to a breathable sand mold for fused bricks and a preparation method thereof. Background Art

[0002] In the production of refractory materials of varying specifications, sand molds are key components, and their quality directly impacts the quality of the final product. Currently, sand molds are mostly made of high-purity silica sand or white corundum. These materials are widely used in refractory production due to their excellent high-temperature resistance and chemical stability.

[0003] When sand mold sand particles are exposed to extreme pouring temperatures exceeding 1800°C, they experience severe thermal shock and physical wear. The high temperatures incinerate some of the original 20- to 70-mesh granules into a fine powder. As the number of recycling cycles increases, the proportion of fine powder in the sand mold material increases. This excessively fine powder can cause numerous drawbacks in sand molds, the most prominent of which is that it limits the mold's air permeability.

[0004] The permeability of sand molds is crucial to the casting process. During the pouring process, contact between the molten metal and the sand mold generates a large amount of gas. If the sand mold is not breathable, this gas cannot be discharged in time, forming pores on the surface of the product. The appearance of pores not only affects the appearance quality of the product but also reduces its mechanical and refractory properties, resulting in substandard products and significant economic losses for the company. Therefore, when making sand molds, it is necessary to separate the fine powder from the recycled sand to ensure the permeability of the sand mold.

[0005] However, simply isolating fines cannot fully meet the needs of businesses. On the one hand, directly discarding fines not only results in a significant waste of resources and increased production costs, but also generates a large amount of solid waste, placing a heavy burden on the environment. Given the increasingly stringent environmental protection requirements, reducing solid waste emissions has become a social responsibility that businesses must shoulder. On the other hand, fines themselves have value. Finding a suitable method to reuse them in sand molds would not only recycle resources but also further reduce costs. Summary of the Invention

[0006] The invention provides a breathable sand mold for fused bricks and a preparation method thereof, so as to solve the technical problem in the prior art that fine sand powder in solid waste sand is inconvenient to be recycled and reused.

[0007] To solve the above problems, the present invention provides a breathable sand mold for fused bricks and a preparation method thereof, which adopts the following technical solutions: A breathable sand mold for fused bricks comprises the following components in percentage by weight: 90%-96% of solid waste sand and 4%-10% of diversified breathable particles.

[0008] The diversified breathable particles include the following components in weight percentage: 32%-36% aluminum dihydrogen phosphate, 29%-33% white sugar, and 35%-38% calcium hydroxide.

[0009] Among them, the particle size of white sugar is 0.5mm to 1mm.

[0010] Wherein, the particle size of calcium hydroxide is 300 mesh.

[0011] Furthermore, it includes the following components in weight percentage: 95% solid waste sand and 5% diversified breathable particles.

[0012] Furthermore, the diversified breathable particles include the following components in weight percentage: 33% aluminum dihydrogen phosphate, 30% white sugar, and 37% calcium hydroxide.

[0013] Furthermore, the aluminum dihydrogen phosphate is a solution and the mass percentage of aluminum dihydrogen phosphate in the aluminum dihydrogen phosphate solution is 50%.

[0014] Furthermore, the solid waste raw sand is high-purity silica sand or white corundum.

[0015] A method for preparing the above-mentioned fused brick breathable sand mold comprises the following steps: S1. Prepare diversified breathable particles: put appropriate amounts of white sugar, calcium hydroxide and aluminum dihydrogen phosphate into a wheel mixer in sequence, stir, and then let it stand.

[0016] The materials in S2 and S1 will clump after being allowed to stand. Place the materials in a blender and stir until the particles are evenly dispersed.

[0017] Furthermore, the stirring time in S1 is 5-10 min.

[0018] Furthermore, the standing time in S1 is 1 hour.

[0019] The beneficial effects of the fused brick breathable sand mold and the preparation method thereof provided by the present invention are: This invention effectively addresses the problem of reusing fine sand powder from solid waste sand in sand molds. Through the "solid waste fine powder regeneration + diversified breathable particles" technology, it achieves efficient reuse of fine powder and optimizes air permeability. The present invention's fused brick breathable sand mold improves air permeability and prevents surface defects. During casting, white sugar burns at high temperatures to form voids, improving the sand mold's air permeability but also releasing CO2. Calcium hydroxide absorbs this CO2, effectively preventing surface porosity or contamination caused by CO2, thereby ensuring the surface quality of the sand mold. The white sugar particle size must be moderate. A lack of white sugar or too fine a particle size results in excessively small voids and poor air permeability, hindering gas evacuation during casting and reducing the yield. If the white sugar particles are too coarse, combustion creates large, sparse pores, resulting in locally excessive air permeability and weakening the overall bonding strength of the sand mold, making sand washout or collapse more likely during casting. Furthermore, coarse pores allow for instantaneous gas expulsion during molten metal pouring, potentially entraining slag or inducing turbulence, increasing the risk of porosity. Furthermore, CO₂ diffuses too rapidly in coarse pores, preventing calcium hydroxide from fully adsorbing it, also leading to porosity defects. Therefore, the synergistic effect of sugar and calcium hydroxide, at the appropriate sugar particle size, ensures breathability while avoiding the various problems associated with CO₂.

[0020] In the present invention, the concentration of the aluminum dihydrogen phosphate solution needs to be moderate. If the concentration is too low, it will lead to insufficient bonding strength, easy collapse of the sand mold, collapse of the sand mold during casting, and unqualified casting size. Only by maintaining an appropriate concentration can it work together with the white sugar component to play a role in enhancing the strength of the sand mold. Among them, aluminum dihydrogen phosphate forms a ceramic binding phase at high temperature, which can enhance the strength of the sand mold. White sand Sugar has a certain adhesion effect, and works together with aluminum dihydrogen phosphate to further enhance the strength of the sand mold and ensure the stability of the sand mold during the casting process. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0022] The principles and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention.

[0023] Example 1 of a breathable sand mold for fused bricks provided by the present invention: Including 95% solid waste raw sand and 5% diversified breathable particles.

[0024] The diversified breathable particles include the following components in weight percentage: 33% aluminum dihydrogen phosphate, 30% white sugar, and 37% calcium hydroxide.

[0025] Among them, the particle size of white sugar is 0.5mm to 1mm.

[0026] Among them, the particle size of calcium hydroxide is 300 mesh.

[0027] The aluminum dihydrogen phosphate is a solution and the mass percentage of the aluminum dihydrogen phosphate in the aluminum dihydrogen phosphate solution is 50%.

[0028] The solid waste raw sand is powder particles formed by the breakage of the original sand mold during recycling, and the powder particle size is less than 100 mesh. In this embodiment, the solid waste raw sand is high-purity silica sand.

[0029] The above-mentioned method for preparing the fused brick breathable sand mold comprises the following steps: S1. Prepare diversified breathable particles: Take appropriate amounts of white sugar, calcium hydroxide and aluminum dihydrogen phosphate and put them into a wheel mixer in sequence and stir for 5 minutes, then let it stand for 1 hour.

[0030] The materials in S2 and S1 will clump after being allowed to stand. Place the materials in a blender and stir until the particles are evenly dispersed.

[0031] Example 2 of a breathable sand mold for fused bricks provided by the present invention: The difference between Example 2 and Example 1 is that Example 2 comprises 90% solid waste sand and 10% diversified breathable particles.

[0032] The solid waste raw sand is powder particles formed by the breakage of the original sand mold during recycling. In this embodiment, the solid waste raw sand is white corundum material.

[0033] Example 3 of a breathable sand mold for fused bricks provided by the present invention: The difference between Example 2 and Example 1 is that Example 2 comprises 96% solid waste sand and 4% diversified breathable particles.

[0034] Example 4 of a breathable sand mold for fused bricks provided by the present invention: The difference between Example 4 and Example 1 is that the diversified breathable particles include the following components in weight percentage: 32% aluminum dihydrogen phosphate, 33% white sugar, and 35% calcium hydroxide.

[0035] Example 5 of a breathable sand mold for fused bricks provided by the present invention: The difference between Example 5 and Example 1 is that the diversified breathable particles include the following components in weight percentage: 33% aluminum dihydrogen phosphate, 29% white sugar, and 38% calcium hydroxide.

[0036] Example 6 of a breathable sand mold for fused bricks provided by the present invention: The difference between Example 6 and Example 1 is that the diversified breathable particles include the following components in weight percentage: 36% aluminum dihydrogen phosphate, 29% white sugar, and 35% calcium hydroxide.

[0037] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the diversified breathable particles further include calcium hydroxide and aluminum dihydrogen phosphate.

[0038] Comparative Example 2 The difference between Comparative Example 1 and Example 1 is that the particle size of the white granulated sugar is less than 0.5 mm.

[0039] Comparative Example 3 The difference between Comparative Example 1 and Example 1 is that the particle size of the white granulated sugar is greater than 1 mm.

[0040] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that aluminum dihydrogen phosphate is a solution and the mass percentage of aluminum dihydrogen phosphate in the aluminum dihydrogen phosphate solution is 45%.

[0041] The sand molds of Examples 1-6 and Comparative Examples 1-4 were cast and the air permeability was tested and the surface quality was observed.

[0042] As shown in the table: sample Breathability Porosity after casting Surface quality Porosity distribution Strength after pouring Example 1 excellent high smooth Uniform high Example 2 excellent high smooth Uniform high Example 3 excellent high smooth Uniform high Example 4 excellent high smooth Uniform high Example 5 excellent high smooth Uniform high Example 6 excellent high smooth Uniform high Comparative Example 1 Poor Low A small amount of pores Overcrowding middle Comparative Example 2 Poor Low A small amount of pores Overcrowding middle Comparative Example 3 good middle Rough Uneven weak Comparative Example 4 excellent high Rough Uniform weak The mechanism of action of the embodiments of the present invention is that during casting, the white sugar component burns at high temperatures, forming voids that improve air permeability, but also releases CO2. The calcium hydroxide component absorbs CO2, preventing surface pores or contamination caused by CO2. Aluminum dihydrogen phosphate forms a ceramic bonding phase at high temperatures, enhancing the strength of the sand mold. Because white sugar has a certain adhesive effect, the white sugar and aluminum dihydrogen phosphate synergistically enhance the strength of the sand mold.

[0043] Combining the analysis of the embodiment and comparative examples 1 and 2, the lack of white sugar or the too fine particle size of white sugar will result in too small a gap and poor air permeability. At this time, the gas cannot be discharged smoothly during casting, and the yield rate decreases.

[0044] Combining the examples and comparative example 3, we found that the coarse particles of white sugar form large, sparse pores after combustion, resulting in locally excessive permeability and a decrease in sand mold strength. Large pores weaken the overall bonding strength of the sand mold, making it prone to sand washout or collapse during casting. Furthermore, coarse pores allow for instantaneous gas discharge during molten metal pouring, potentially entraining slag or inducing turbulence, which in turn increases the risk of pores. Finally, CO2 diffuses too rapidly in coarse pores, preventing calcium hydroxide from being fully adsorbed, leading to pore defects.

[0045] Combining the examples and comparative example 3, the solubility of the aluminum dihydrogen phosphate solution was too low, resulting in insufficient bonding strength and easy collapse of the sand mold. The sand mold collapsed during casting and the casting size was unqualified.

Claims

1. A breathable sand mold for fused bricks, characterized in that: It includes the following components in weight percentage: solid waste sand 90%-96%, diversified breathable particles 4%-10%; The diversified breathable particles include the following components in percentage by weight: 32%-36% aluminum dihydrogen phosphate, 29%-33% white sugar, and 35%-38% calcium hydroxide; Among them, the particle size of white sugar is 0.5mm to 1mm; Wherein, the particle size of calcium hydroxide is 300 mesh.

2. The fused brick breathable sand mold according to claim 1, characterized in that: The invention comprises the following components in weight percentage: 95% of solid waste sand and 5% of diversified breathable particles.

3. The fused brick breathable sand mold according to claim 2, characterized in that: The diversified breathable particles include the following components in weight percentage: 33% aluminum dihydrogen phosphate, 30% white sugar, and 37% calcium hydroxide.

4. The fused brick breathable sand mold according to claim 3, characterized in that: The aluminum dihydrogen phosphate is a solution and the mass percentage of aluminum dihydrogen phosphate in the aluminum dihydrogen phosphate solution is 50%.

5. The fused brick breathable sand mold according to claim 1, characterized in that: The solid waste raw sand is high-purity silica sand or white corundum.

6. A method for preparing a breathable sand mold for fused bricks according to any one of claims 1 to 5, characterized in that: The steps include: S1. Prepare diversified breathable particles: Place appropriate amounts of white sugar, calcium hydroxide, and aluminum dihydrogen phosphate into a wheel mixer, stir, and then let stand; The materials in S2 and S1 will clump after being allowed to stand. Place the materials in a blender and stir until the particles are evenly dispersed.

7. The method for preparing a breathable sand mold for fused bricks according to claim 6, wherein: The stirring time in S1 is 5-10 min.

8. The method for preparing a breathable sand mold for fused bricks according to claim 6, wherein: The standing time in S1 is 1 h.