METHODS FOR REDUCING METAL OXIDATION WHEN MELTING ALUMINUM ALLOYS

Abstract

The process of melting and pouring aluminum alloys is usually carried out at a temperature range from 680 to 730 0C. However, due to the great relationship of aluminum and oxygen at these temperatures, strong oxidation of the metal and saturation of the melt with oxide inclusions occur. In recent years, technologies for melting aluminum alloys have been developed to reduce the oxidation of metal with oxygen. One of these new technologies is the melting and processing of aluminum alloy at temperatures using carbon as a reducing agent. This article reveals the results of the research on the development of flux composition for melting aluminum waste. The authors have demonstrated the melting unit diagram and the results of their studies on identification of the temperature mode for melting aluminum scrap. For electric unit with mobile and fixed electrodes, the modes for heating and loading metal and modes for melting aluminum and its waste have been given. The article describes the research results and recommendations, according to which the smelting chamber temperature must be maintained at 1,000-1,100 °C, and the melting zone temperature – at 1,400-1,500 °C. It is also recommended to load the aluminum waste after the flux melting and at flux temperature not less than 700-750 °C. Table 1 shows the flux compositions that allow for aluminum melting process in different melting units. In the conclusion, the authors state that the application of melting unit design in aggregate with graphite electrodes and protective flux provides: reduced irretrievable burn-off loss, reduced energy costs, and improved quality of the melt due to reduced content of oxide and gas inclusions in the melt composition [1-4].