Efficient environment-friendly granular aluminum alloy flux and preparation method thereof

Abstract

The present application belongs to the technical field of nonferrous metallurgy flux, and discloses a high-efficiency environment-friendly granular aluminum alloy flux and a preparation method thereof. The high-efficiency environment-friendly granular aluminum alloy flux comprises, by mass percentage, 25-55% of MgCl2, 35-70% of KCl, and 5-20% of active potassium halide, and the total amount is 100%. The preparation method comprises the following steps: uniformly mixing MgCl2, KCl and active potassium halide in a certain proportion to obtain a mixture; gradually heating the mixture to 450-650 DEG C to melt and keep warm for 30-60 min; naturally cooling the melt to below 150 DEG C to obtain a solid blocky material; crushing and screening the solid blocky material to obtain the high-efficiency environment-friendly granular aluminum alloy flux, and then sealing and packaging the flux particles to obtain a finished product. The aluminum alloy flux has the characteristics of not easy to absorb moisture, good refining effect, good aluminum slag separation effect and small smoke, and can be widely used in aluminum and aluminum alloy production.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metallurgical flux technology, specifically to a high-efficiency and environmentally friendly granular aluminum alloy flux that is not prone to moisture absorption, has good refining effect, good aluminum slag separation effect, and low flue gas emission, as well as its preparation method. Background Technology

[0002] Aluminum and aluminum alloys are widely used in aviation, aerospace, automotive, rail transportation, shipbuilding, machinery manufacturing, chemical, building decoration, packaging, sporting goods and other fields due to their low density, high strength, good plasticity, and excellent electrical conductivity, thermal conductivity and corrosion resistance. They have become the second most used metal material after steel.

[0003] Aluminum and aluminum alloys exhibit significant hydrogen absorption during the smelting process. During casting solidification, hydrogen atoms readily precipitate, forming bubbles. This leads to defects such as porosity, shrinkage cavities, and cracks in the castings, resulting in reduced mechanical properties, machinability, corrosion resistance, and surface quality. Furthermore, the molten aluminum and aluminum alloys readily react with air to form oxides. The inclusion of these oxides in the melt reduces its purity, leading to oxide inclusions in the castings and further degrading performance. Therefore, refining agents are typically added during the smelting of aluminum and aluminum alloys to remove gases and oxide inclusions from the melt, and slag-removing agents are used to improve the separation of the melt from the slag, thereby increasing the purity of the molten aluminum alloy.

[0004] Currently, most aluminum and aluminum alloy fluxes (refining agents, slag removers) are powdered mixtures, which generate a large amount of smoke and dust during use, posing a significant risk to human health and the environment. With increasing national environmental protection enforcement and growing environmental awareness among enterprises, aluminum alloy manufacturers are demanding more efficient and environmentally friendly fluxes. As a result, granular aluminum and aluminum alloy fluxes have emerged in existing technologies. These are mostly produced by high-temperature melting and mixing, followed by solidification into blocks, and then crushing to obtain granular products. Because they produce less smoke during use than powdered fluxes, they have become the preferred flux for an increasing number of aluminum alloy manufacturers. However, existing granular aluminum alloy fluxes are mainly composed of various inorganic salts, commonly a mixture of chloride salts with a small amount of fluoride salts. Due to their high sodium salt content, they not only easily cause sodium embrittlement in aluminum alloys, making castings prone to cracking, but also reduce the fluidity of the melt, affecting the casting performance of the alloy. Furthermore, they lead to poor slag-liquid separation, resulting in high aluminum content in the slag, thus reducing the refining effect of aluminum and aluminum alloys. In addition, since the chloride salts that make up the majority of the flux are prone to absorbing moisture from the air, and some chloride salts (such as magnesium chloride) often exist in the form of crystalline hydrates, if the moisture in them cannot be completely removed, it will enter the aluminum alloy melt with the flux and increase the hydrogen content, thereby aggravating casting defects.

[0005] Of course, existing technologies also use mixed fluxes composed of potassium fluoroaluminate, calcium fluoride, potassium carbonate, potassium sulfate, barium sulfate, potassium chloride, and anhydrous aluminum chloride, which can avoid sodium embrittlement and reduce moisture absorption. However, barium sulfate has a high density and is not easy to float and be discharged during use. Moreover, barium sulfate and calcium fluoride can easily introduce impurity elements into the aluminum alloy melt. Furthermore, due to the overly complex composition, the chemical reaction between the flux and the aluminum alloy melt is complicated and difficult to control effectively, and it can also generate polluting SO2 gas. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a highly efficient and environmentally friendly granular aluminum alloy flux that is not prone to moisture absorption, has good refining effect, good aluminum slag separation effect, and low flue gas emission. It also provides a method for preparing the highly efficient and environmentally friendly granular aluminum alloy flux.

[0007] The high-efficiency and environmentally friendly granular aluminum alloy flux of the present invention is achieved as follows: by mass percentage, it comprises 25-55% MgCl2, 35-70% KCl, and 5-20% active potassium halide, with a total amount of 100%.

[0008] Furthermore, the active potassium halide includes one or any combination of KF, KAlF4, K3AlF6, K2TiF6, KNO3, and K2SO4.

[0009] Furthermore, the active potassium halide comprises, by mass percentage: 50-75% K3AlF6, 20-35% K2TiF6, and 5-15% KNO3, with a total amount of 100%.

[0010] Furthermore, the high-efficiency and environmentally friendly granular aluminum alloy flux comprises, by mass percentage: 35-45% MgCl2, 50-60% KCl, and 10-15% active potassium halides, with a total of 100%, wherein the active potassium halides comprise, by mass percentage: 60-70% K3AlF6, 25-30% K2TiF6, and 8-13% KNO3, with a total of 100%.

[0011] The preparation method of the high-efficiency and environmentally friendly granular aluminum alloy flux of the present invention is as follows: it includes the steps of mixing, melting, cooling, pulverizing and packaging, and the specific contents are as follows: A. Mixing: Mix MgCl2, KCl, and active potassium halide evenly according to the mass percentage to obtain a mixture; wherein, the active potassium halide is one or any combination of KF, KAlF4, K3AlF6, K2TiF6, KNO3, and K2SO4; B. Melting: Gradually heat the above mixture to 450-650°C to melt it, and keep the mixture in the molten state for 30-60 minutes; C. Cooling: Allow the heat-insulated melt to cool naturally to below 150°C to obtain solid block material; D. Crushing and Packaging: The above solid block material is crushed and screened to obtain a high-efficiency and environmentally friendly granular aluminum alloy flux. The flux particles are then sealed and packaged to obtain the finished high-efficiency and environmentally friendly granular aluminum alloy flux.

[0012] Furthermore, in the mixing step, the particle size of MgCl2 is 0.10~0.20 mm, the particle size of KCl is 0.02~0.10 mm, and the particle size of active potassium halide is 0.05~0.20 mm.

[0013] Furthermore, in the melting step, the mixture is added to a crucible or furnace at a temperature not exceeding 100°C, and then stirred while heating until the mixture reaches a preset temperature or is completely melted, after which stirring is stopped.

[0014] Furthermore, in the crushing and packaging step, the crushed solid block material is screened to obtain high-efficiency and environmentally friendly granular aluminum alloy flux with a particle size of 1-2 mm. Particles with a particle size greater than 2 mm after screening are crushed and screened again, while particles with a particle size less than 1 mm after screening are returned to the melting step for remelting.

[0015] Furthermore, in the crushing and packaging step, the solid block material is crushed using a cone crusher and / or a hammer crusher.

[0016] The beneficial effects of this invention are as follows: 1. The flux of the present invention forms granular flux, which generates less smoke and dust during use; through the optimization of flux composition, it not only contains no sodium salt to reduce sodium embrittlement, but also reduces the amount used by 30-45% compared with traditional flux, and can also reduce the amount of aluminum slag produced. Furthermore, the components in the flux will generate a large amount of heat during use, thereby improving the fluidity of aluminum slag in the melt, which helps to separate slag from aluminum and improves the purity of the melt.

[0017] 2. The flux of the present invention utilizes the fluoride salts in magnesium chloride and active potassium halide to form complexes with magnesium oxide and aluminum oxide in the aluminum alloy melt, thereby removing non-metallic inclusions in the melt; and utilizes the magnesium chloride and potassium chloride to adjust the melting temperature, density and fluidity of the flux, so that the flux can float from the aluminum alloy melt and spread on the surface, which can not only reduce the oxidation loss on the surface of the aluminum alloy melt, but also make the aluminum slag float to improve the separation effect between the melt and the slag, thereby further improving the purity of the aluminum alloy melt.

[0018] 3. The flux preparation method of the present invention involves mixing the components evenly and then gradually heating them to melt and holding them at the temperature. During the gradual heating process, the moisture can be removed. In particular, by stirring during the heating process and holding the melt at the temperature, the moisture can be completely removed and the components can be evenly distributed in the melt. Furthermore, the components are melted and form solid blocks and then crushed into particles, which reduces the contact area between the hygroscopic chloride salts and water vapor, thereby significantly reducing the hygroscopicity of the flux of the present invention.

[0019] In summary, the present invention has the characteristics of being non-hygroscopic, having good refining effect, good aluminum slag separation effect, and low flue gas emissions. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] The high-efficiency and environmentally friendly granular aluminum alloy flux of the present invention comprises, by mass percentage: 25-55% MgCl2, 35-70% KCl, and 5-20% active potassium halide, with a total amount of 100%.

[0022] The active potassium halide includes one or any combination of KF, KAlF4, K3AlF6, K2TiF6, KNO3, and K2SO4.

[0023] The active potassium halide comprises, by mass percentage: 50-75% K3AlF6, 20-35% K2TiF6, and 5-15% KNO3, with a total amount of 100%.

[0024] The high-efficiency and environmentally friendly granular aluminum alloy flux comprises, by mass percentage: 35-45% MgCl2, 50-60% KCl, and 10-15% active potassium halides, with a total of 100%. The active potassium halides comprise, by mass percentage: 60-70% K3AlF6, 25-30% K2TiF6, and 8-13% KNO3, with a total of 100%.

[0025] The preparation method of the high-efficiency and environmentally friendly granular aluminum alloy flux of the present invention is as follows: it includes the steps of mixing, melting, cooling, pulverizing and packaging, and the specific contents are as follows: A. Mixing: Mix MgCl2, KCl, and active potassium halide evenly according to the mass percentage to obtain a mixture; wherein, the active potassium halide is one or any combination of KF, KAlF4, K3AlF6, K2TiF6, KNO3, and K2SO4; B. Melting: Gradually heat the above mixture to 450-650°C to melt it, and keep the mixture in the molten state for 30-60 minutes; C. Cooling: Allow the heat-insulated melt to cool naturally to below 150°C to obtain solid block material; D. Crushing and Packaging: The above solid block material is crushed and screened to obtain a high-efficiency and environmentally friendly granular aluminum alloy flux. The flux particles are then sealed and packaged to obtain the finished high-efficiency and environmentally friendly granular aluminum alloy flux.

[0026] In the mixing step, the particle size of MgCl2 is 0.10~0.20mm, the particle size of KCl is 0.05~0.10mm, and the particle size of active potassium halide is 0.02~0.20mm.

[0027] In the melting step, the mixture is added to a crucible or furnace at a temperature not exceeding 100°C, and then stirred while heating until the mixture reaches the preset temperature or is completely melted, after which stirring is stopped.

[0028] In the crushing and packaging step, the crushed solid block material is screened to obtain high-efficiency and environmentally friendly granular aluminum alloy flux with a particle size of 1-2 mm. Particles with a particle size greater than 2 mm after screening are crushed and screened again, while particles with a particle size less than 1 mm after screening are returned to the melting step for remelting.

[0029] In the crushing and packaging step, the solid block material is crushed using a cone crusher and / or a hammer crusher.

[0030] Example 1 S100: Mix 25% MgCl2, 70% KCl, and 5% active potassium halide by mass percentage to obtain a mixture; wherein, the active potassium halide by mass percentage includes: 60% K3AlF6, 30% K2TiF6, and 10% KNO3, the particle size of MgCl2 is 0.15 mm, the particle size of KCl is 0.10 mm, and the particle size of active potassium halide is 0.20 mm.

[0031] S200: Place the above mixture into a graphite steel pot, and gradually heat it from room temperature to 450°C while stirring to melt it. Keep the mixture at 450°C in a molten state for 60 minutes.

[0032] S300: The heat-preserved melt is naturally cooled to below 50°C in a graphite steel pot to obtain a solid block material.

[0033] S400: The above solid block material is crushed using a hammer crusher, and then the crushed material is screened to obtain a high-efficiency and environmentally friendly granular aluminum alloy flux with a particle size of 1-2mm. The flux particles are then sealed and packaged to obtain the finished product. Particles with a particle size greater than 2mm after screening are crushed and screened again, and particles with a particle size less than 1mm after screening are returned to the melting step to participate in the melting of the next batch of mixture.

[0034] As shown in Table 1, the water absorption rate of the above-mentioned high-efficiency and environmentally friendly granular aluminum alloy flux products was compared in an experiment.

[0035] Table 1 Comparison of Water Absorption Rate

[0036] Among them: Comparative Sample 1 is a domestically produced granular aluminum alloy flux, and Comparative Sample 2 and Comparative Sample 3 are two foreign granular aluminum alloy flux products.

[0037] Example 2 S100: Mix 55% MgCl2, 35% KCl, and 10% active potassium halide by mass percentage to obtain a mixture; wherein, the active potassium halide by mass percentage includes: 75% K3AlF6, 20% K2TiF6, and 5% KNO3, the particle size of MgCl2 is 0.1 mm, the particle size of KCl is 0.02 mm, and the particle size of active potassium halide is 0.1 mm.

[0038] S200: Place the above mixture into a graphite steel pot, and gradually heat it from room temperature to 500°C while stirring to melt it. Keep the mixture at 500°C in a molten state for 50 minutes.

[0039] S300: The heat-preserved melt is naturally cooled to below 100°C in a graphite steel pot to obtain a solid block material.

[0040] S400: The above solid block material is coarsely crushed by a cone crusher and finely crushed by a hammer crusher. The crushed material is then screened to obtain a high-efficiency and environmentally friendly granular aluminum alloy flux with a particle size of 1-2 mm. The flux particles are then sealed and packaged to obtain the finished product. Particles with a particle size greater than 2 mm after screening are crushed and screened again. Particles with a particle size less than 1 mm after screening are returned to the melting step to participate in the melting of the next batch of mixture.

[0041] As shown in Table 2, the water absorption rate of the above-mentioned high-efficiency and environmentally friendly granular aluminum alloy flux products was compared in an experiment.

[0042] Table 2 Comparison of Water Absorption Rate (Part 2)

[0043] Among them: Comparative Sample 1 is a domestically produced granular aluminum alloy flux, and Comparative Sample 2 and Comparative Sample 3 are two foreign granular aluminum alloy flux products.

[0044] Example 3 S100: Mix 40% MgCl2, 30% KCl, and 20% active potassium halide by mass percentage to obtain a mixture; wherein, the active potassium halide by mass percentage includes: 50% K3AlF6, 35% K2TiF6, and 15% KNO3, the particle size of MgCl2 is 0.2 mm, the particle size of KCl is 0.05 mm, and the particle size of active potassium halide is 0.05 mm.

[0045] S200: Place the above mixture into a graphite steel pot, and gradually heat it from room temperature to 650°C while stirring to melt it. Keep the mixture at 650°C in a molten state for 30 minutes.

[0046] S300: The heat-preserved melt is naturally cooled to below 150°C in a graphite steel pot to obtain a solid block material.

[0047] S400: The above solid block material is crushed using a hammer crusher, and then the crushed material is screened to obtain a high-efficiency and environmentally friendly granular aluminum alloy flux with a particle size of 1-2mm. The flux particles are then sealed and packaged to obtain the finished product. Particles with a particle size greater than 2mm after screening are crushed and screened again, and particles with a particle size less than 1mm after screening are returned to the melting step to participate in the melting of the next batch of mixture.

[0048] As shown in Table 3, the water absorption rate of the above-mentioned high-efficiency and environmentally friendly granular aluminum alloy flux products was compared in an experiment.

[0049] Table 3 Comparison of Water Absorption Rates (Part 3)

[0050] Among them: Comparative Sample 1 is a domestically produced granular aluminum alloy flux, and Comparative Sample 2 and Comparative Sample 3 are two foreign granular aluminum alloy flux products.

[0051] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-efficiency and environmentally friendly granular aluminum alloy flux, characterized in that... The active ingredient comprises, by mass percentage: 25–55% MgCl2, 35–70% KCl, and 5–20% active component, with a total amount of 100%. The active component consists of K3AlF6, K2TiF6, and KNO3, with K3AlF6 comprising 60–70%, K2TiF6 25–30%, and KNO3 8–13% by mass, and the total amount of active component is 100%. The preparation method of the high-efficiency and environmentally friendly granular aluminum alloy flux includes the steps of mixing, melting, cooling, pulverizing and packaging, as follows: A. Mixing: Mix MgCl2, KCl, and the active components evenly according to the mass percentage to obtain a mixture; wherein, the active components are K3AlF6, K2TiF6, and KNO3; B. Melting: Gradually heat the above mixture to 450-650°C to melt it, and keep the mixture in the molten state for 30-60 minutes; C. Cooling: Allow the heat-insulated melt to cool naturally to below 150°C to obtain solid block material; D. Crushing and Packaging: The above solid block material is crushed and screened to obtain high-efficiency and environmentally friendly granular aluminum alloy flux. Then, the flux particles are sealed and packaged to obtain the finished high-efficiency and environmentally friendly granular aluminum alloy flux. In the mixing step, the particle size of MgCl2 is 0.10~0.20mm, the particle size of KCl is 0.02~0.10mm, and the particle size of the active component is 0.05~0.20mm; In the melting step, the mixture is added to a crucible or furnace at a temperature not exceeding 100°C, and then stirred while heating until the mixture reaches the preset temperature or is completely melted, after which stirring is stopped. In the crushing and packaging step, the crushed solid block material is screened to obtain a high-efficiency and environmentally friendly granular aluminum alloy flux with a particle size of 1-2 mm. Particles with a particle size greater than 2 mm after screening are crushed and screened again, while particles with a particle size less than 1 mm after screening are returned to the melting step for remelting. In the crushing and packaging step, the solid block material is crushed using a cone crusher and / or a hammer crusher.

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