Recycling aluminum alloy purification

As we all know, the recycling of aluminum waste has so far rarely gone the process of primary aluminum, that is, the reduction of electrolysis, the main reason is that the economy can not be used. Because the recycling of waste aluminum is costly. It is generally reported that the recycled aluminum recycling power consumption is only 5% of primary aluminum, and refers only to the energy consumed for the recycling of scrap aluminum and scrap aluminum and the transportation. The energy required for electrolytic aluminum is far greater than this, and usually the electricity consumption per ton of aluminum electrolysis is 13,000 to 15,000 kilowatt hours, and the energy cost will be considerable. At the same time, due to the presence of a number of additional elements that are not found in the ore in the waste aluminum, this will cause problems for recycling, and even the general process cannot achieve the purpose of restoring the purity of the primary aluminum. Considering various factors, the current process of aluminum recycling in various countries is scrap aluminum-decomposition-treatment-remelting-recycled aluminum alloys with different grades of components. Of course, there are difficulties in controlling and preparing the ingredients in the above process. Therefore, the issue of purification and purification during remelting is still a common issue explored by the aluminum industry. In addition to taking a variety of treatment before the waste aluminum in the melting furnace to avoid impurities, foreign elements into other measures, but also need to study in accordance with product needs, process needs in the melting process to reduce the content of impurity elements and some of the original alloying elements, Make it with the production target alloy composition standard requirements. At present, the most common method is to purify the raw materials before furnace analysis, carefully prepared, divided into multiple feeding, strengthen the stirring during melting, strengthen the pre-furnace analysis, strengthen the refining of the furnace, static furnace flux refining, etc., to ensure the internal purity of the metal, to ensure product quality , increase real yield. Strengthen the analysis and classify the original scrap aluminum according to the composition. Separate use is one of the most powerful measures to ensure the quality of the chemical composition of products. After analyzing the comprehensive standards or the wastes and scraps in the factory, use it after analyzing the remelted or recycled ingots after packing. Melt purification is a very important process. The internal purity of the waste aluminum is poor, and it contains oxide films in varying degrees. Some surfaces are seriously polluted with water, oil stains, paint, and dust, and can easily enter the melt to form combing inclusion defects. , Affecting the final performance of castings, must strengthen the melt purification treatment. Some methods have different effects on the removal of hydrogen, non-metallic inclusions and sodium and other foreign bodies. It is very difficult to extract the original alloy elements in the waste aluminum, but it is rarely reported. However, some alloy elements may be used to influence the properties of the alloy to adjust the control. For example, Mg and Si form a Mg2Si compound strengthening phase. The Mg/Si weight ratio of the composition of Mg2Si is 1.73. When Mg2Si>1.73, the solid solubility of Mg2Si in the alloy will be affected and the heat treatment effect will be weakened. Excess Si has no effect. When Fe and Si exist simultaneously, a ternary compound is formed. When Fe> Si is formed, more α-brittle phase Al2Fe3Si2 is formed;
Fe