Analysis on the purification treatment method and precautions of recycled aluminum alloy


The recycling of waste aluminum has so far rarely followed the process of primary aluminum, that is, reduction of electrolysis, the main reason is that it cannot be economically planned. Because the recycling of waste aluminum is expensive. It is generally reported that the recycled aluminum recycling power consumption is only 5% of the original aluminum, which only refers to the energy consumed by melting waste aluminum, waste aluminum recycling and transportation. The energy required for electrolytic aluminum is much larger than this. Usually, the electricity consumption per ton of aluminum is 13,000 to 15,000 kWh, and the energy cost will be considerable. At the same time, due to the presence of many added elements in the waste aluminum, which will bring trouble to the recycling, even the general process can not achieve the purpose of restoring the purity of the original aluminum. Considering various factors, the process of reclaiming aluminum in various countries today is a waste aluminum-decomposition-treatment-remelting-recycled aluminum alloy with different grades. Of course, the above process procedures have difficulties in that components are difficult to control and formulate.

Therefore, the problem of purification and purification during remelting is still a subject that everyone in the reclaimed aluminum industry has jointly explored. In addition to taking various treatments before waste aluminum in the melting furnace to avoid impurities, foreign elements entering, etc., it is necessary to study the content of impurities and certain raw alloy elements in the melting process according to product needs and process requirements. Make it meet the production requirements of the target alloy composition standards. At present, the most common method is to analyze the raw materials before the furnace, carefully prepare, add multiple materials, strengthen the mixing during melting, strengthen the pre-furnace analysis, strengthen the refining and refining, and refine the furnace to ensure the purity of the metal and ensure the quality of the product. , improve the yield. Intensify the analysis and classify the original waste aluminum by component classification. Separate use is one of the most powerful measures to ensure the quality of the chemical composition of the product. After analysis of the comprehensive standard or the waste and scrap in the plant, it is re-melted or regenerated after being packaged and then used according to the analysis.

Melt purification is an important process. The internal purity of waste aluminum is poor, and the oxide film is contained to varying degrees. Some surfaces are seriously polluted by water, grease, paint and dust, and easily enter the melt to form a comb-inclusion defect. Influencing the final performance of the casting, it is necessary to strengthen the melt purification treatment.

Some methods have different effects on foreign matters such as hydrogen, non-metallic inclusions and sodium. It is extremely difficult to extract the original alloying elements in waste aluminum, but it is rarely reported, but sometimes the relationship between some alloying elements can be used to influence the alloy properties for adjustment control. For example, Mg and Si form a Mg2Si compound strengthening phase. The Mg/Si weight ratio of the composition of Mg2Si was 1.73. When Mg2Si>1.73, it will affect the solid solubility of Mg2Si in the alloy and weaken the heat treatment effect. Excess Si has no effect. When Fe and Si exist simultaneously, a ternary compound is formed, and when Fe>Si, a large amount of α-brittle phase al2Fe3Si2) is formed.

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